Welcome to the crucible. If you haven't completed lesson 1 yet, you should go and do that first.
This exercise is probably what Drawabox is best known for (and perhaps most reviled). Which is kind of unfortunate, given that it's a pretty basic exercise. As one might imagine, you draw a box - then do it again another 249 times.
I cover it (partially) in my notes about the organic perspective exercise, but before we get to drawing, I don't want you leaving thinking that this is all there is to the exercise. Some people rush off without getting all the instructions, and fail to make the most of the arduous task. There's a little more to it, which is explained in the video as well as below.