This parsha continues after the dedication of the Mishkan by the princes of the tribes in the previous parsha, Nasso.
This first aliyah begins with G-d's commandment to Moshe to tell Aharon to light the Menorah in such a way as to illuminate the Menorah itself, which is made out of a single piece of beaten gold.
The aliyah then continues with instructions for an elaborate inauguration procedure for all the Leviim. The inauguration procedure included shaving their entire bodies with a razor (some commentaries say this didn't include their beards and peyos), then immersion in a mikvah. The Leviim are then to come to the tent of meeting where all the Jewish people would place their hands on the Leviim. The Leviim would then be designated as a wave offering of the Jewish people. After all that, the Leviim would become the ones to perform G-d's service in the Mishkan.
In the second aliyah G-d says again that he is taking the Leviim instead of the first-born Jews. G-d says that the first-born Jews became His on the day that G-d killed all the first born Egyptians and protected all the first born Jews. Then Moshe, Aharon, and all the Jewish people follow the inauguration procedure described in the previous aliyah (where the Leviim shave, immerse in the mikvah, and the Jewish people place their hands on the Leviim). Then Aharon lifts each individual Levi and waves him up and down, back and forth (like a lulav is waved on Succos). Miraculously Aharon waves all 22,000 Leviim in one day!
Following the above, this aliyah continues with another detail of the service of the Leviim; and that is that they should serve from 25 years old to 50 years old. From 25 to 30 they learned the service they were to perform, and from 30 to 50 they performed it.
Rashi points out that this third aliyah begins by describing what takes place in the month of Nissan in the second year after leaving Egypt, while the book of Bamidbar (starting a few parshas earlier) started one month later. This shows once again that the Torah is not necessarily written in chronological order.
In this aliyah G-d tells Moshe about the holiday of Pesach and all its statutes and ordinances and the Jewish people do them and observe Pesach. However, certain men cannot participate because they are tamai- mais (impure because of contact with a dead body) and therefore cannot participate with everyone else in the festivities.
These men feel bad that they cannot participate, so Moshe asks G-d about the matter, and G-d says that whoever is tamai mais, or far away, "to you or to your generations", gets a second chance one month later to observe the Pesach. This is the holiday of Pesach sheni that we observe on the 14th of Iyar, (shortly before Lag B'omer), when we eat some our leftover matzo from Pesach.
The Chassidic point of these words describing the second Pesach is that "it is never too late", all is never lost, one can always correct past actions. Even if one is defiled, even if one is far away, and even if this is "to you", that is to say, by your own choice and desire, it is nonetheless possible to rectify matters if the desire to do so is sincere.
The fourth aliyah describes the Divine signs that signal that the Jews should move their camp. From the day the Mishkan was erected a cloud covered the Mishkan by day and a fire by night. Whenever the cloud lifted up they would journey, and whenever it rested they would stop. In some cases the cloud rested for just a few days, or even one night, and at other times the cloud rested a whole year. In all cases the Jewish people trusted in G-d and moved at His bidding.
Next, this aliyah discusses the two silver trumpets Moshe is to make and use. Aharon's sons would blow the trumpets at Moshe's command. Different trumpet blasts meant different things; including assembling the community together for a meeting, or just the princes, or that the camp was to start moving. And when we went to war, a certain trumpet blast would cause us to be remembered by G-d, and then we were delivered from our enemies.
After the previous aliyah discussed the way G-d communicated the traveling of the Jews, in this fifth aliyah the Cloud of Glory rises from the Mishkan for their first trip. At this point the Jewish nation had been camped at Mount Sinai for slightly less than a year, and they departed according to the order of the tribes and procedures for the Leviim outlined recently in the Torah.
At this point everyone, including Moshe, thinks they are just three days from entering Israel, and in this aliyah Moshe pleads with Yisro, his father-in-law, to join them and enter Israel with the Jews, but he declines with thanks. At the end of the aliyah the Torah says that the cloud of G-d was over them by day when they set forward from the camp. Rashi says this actually means seven clouds: one in each of the four directions, one above lowering the high places, one below raising the low places, and one before them killing the serpents and scorpions.
The sixth aliyah begins with an inverted Hebrew letter "nun", then the words "Vay'hi binsoah ha-aron..." which is what the congregation recites as we take out the Torah in the synagogue, then another inverted "nun". The inverted nuns are actually written in the Torah. Rashi says that the inverted nuns show that the verse "Vay'hi binsoah..." is out of place, and only placed here to separate two sins. The first is that the Jews hurried away from Mount Sinai and what would be next to it is the Jews' complaining about conditions in the desert. After that is yet a third sin, murmuring for meat. In Judaism three things in a row make a "chazukah" (a permanent situation, in this case possibly designating the Jews to be permanent sinners). To avoid this three-in-a-row situation, the three are broken up by this nun- delineated passage.
This "nun" delineated passage is such a strong division in the Torah, that some commentators consider the Torah to have seven books instead of five. They are 1) Braishis, 2) Shmos, 3) Vayikra, ) Bamidbar up till Vay'hi binsoah, ) Vay'hi binsoah, ) The balance of Bamidbar after Vay'hi binsoah, and ) Devarim.
So, as we have said, here the Jews are three days away from entering the land of Israel, and now they start complaining about the manna and wishing for the food they were used to in Egypt. G-d promises to give them meat enough for a whole month, until they get sick of it. Moshe asks G-d for help with the people, so G-d appoints seventy elders to share the burden of leading the people with Moshe.
In the seventh aliyah G-d causes a wind to blow, sweeping quail in from the sea. The people gather the quail and start eating the meat. The people who eat the meat gluttonously die of a plague.
Around this time Miriam, Moshe's sister, hears that Moshe had separated from his wife Tzipporah (because of reasons of prophecy), and Miriam speaks against this practice to Aharon because no other prophets did such a thing. G-d considers this loshen hora (evil talk about another) and strikes Miriam with tzora-as. Rashi says that if this is called loshen hora, where Miriam hadn't intended to shame Moshe, how much more so is it when one intends to shame his fellow man.
Moshe then prays that she be cured right away. Nevertheless she is quarantined outside the camp for seven days. When Moshe was put afloat in the Nile as an infant, Miriam waited nearby to see what would happen to him. So, as a reward for what she did as a young girl, midda-keneged-midda (measure for measure) the whole Jewish people wait for her until her cure was complete.
Throughout this whole matter Moshe remains silent and doesn't defend himself, and the Torah calls him the humblest man on earth. Now, how can the man that G-d chose to lead the Jews out of their Egyptian bondage and who received the Torah for them, how can he be the humblest man on earth?
Our Sages explain that Moshe indeed was humble, because he knew that all this wasn't his to be proud of, but that it was G-d Who gave him the opportunity and the ability to do these things. He knew that if G-d had given this opportunity and ability to anybody else that they would have done an even better job.