First, at the prompt you must type:
res checkin prost01You will be asked a series of questions with obvious answers. However, one question will ask you which group you are in. The answer does not matter. You can just type 1.
Second, after you have finished the first step, you type at the prompt:
course join prost01No questions to answer. That is all there is to it.
It is extremely important that you do this as soon as possible. If you don't, you are in danger of missing important, timely information about the course.