My parents told me that once i get dropped off they are gonna want to come on here...how do they create a thing so that others will know they are a parent?

Well they can't register as members because only enrolled students can. About all they can do is post as a guest with some sort of name that makes it clear that they're a parent

how do they do that?

I'm not 100% sure, since I've never posted as a guest, but I think all they have to do is do the normal reply to post or new topic thing and then just fill in a guest name where it asks for one
Why do they want to get on here once you've been dropped off?

idk...its my parents, i dont understand them soetimes....i think its to give others a hand in what to bring to the DC session (since thats where im going) but again, idk...