In the sixth aliyah, the quails appear in the evening.
In the morning, manna appears with a layer of dew above and below it (this is why our Shabbos challah is on top of a board and covered with a challah cover).
The Jews are told to gather one omer (a biblical measure of approximately .5 liters or 5.2 pints) of it, and he who gathers more or less than an omer arrives home with exactly one omer.
They are told not to leave any over till the next day, and those that do so find it rotted with worms.
On Friday they are given two portions of manna, this is a reason why on Shabbos we make the Hamotzi blessing (for bread) over two loaves of challah. They are told to leave over the second portion for Shabbos, and not to leave their premises to look for manna on the Shabbos because there would be none found.
This is when they are given the Shabbos, as a day of rest, and they are told to cook on Friday and lay it up for Shabbos (as in cholent).