I am getting this question frequently.
On the directions for signing up for the AP Test, it asks you to use a join code...
that's the AP Classroom code that I have already given you from the beginning of the year. If you already are joined on AP Classroom, just go to the second part and begin to fill out the test registration site information and pay the fee.
If you are not on AP Classroom - you will find the code and directions on how to sign up in the Schoology folder "Start Here"