Yes. You will add every schools you went to or plan to attend for prereq classes. You'll have a chance to update schools and courses you took/plan to take during Academic Update period so don't worry if you don't know for sure which schools you'll end up taking one or two classes.
For the schools you previously attended, you'll print out a transcript request form for that school on PharmCAS (I think there's a small button once you enter that school) then bring the completed form to your schools' transcript office. Your school will need to include that form when they send your transcript.
If you plan to take some prereq classes later in the cycle, like winter or spring, you will not send the transcripts to PharmCAS but instead will send them to the schools you applied to.