Please start at Conditional Expressions and Programs, and follow the "Next" links (and the corresponding sections in the DrScheme Companion) until you get to the section entitled Compound Data: Lists of Fixed Length, which is where we'll start the next day.
I recommend (but do not require) that you try all of the exercises in the text; they should take only a few minutes apiece. Exercise 4.0.3 is this textbook's equivalent of a Buggle assignment: you write a single function, plug it into a much larger pre-written program, and get to play a game against the computer.