Do the pictures bạn post on các câu lạc bộ have to be yours?

No, they don't.
bạn should credit whoever they belong to hoặc wherever bạn found them though.

Nope my friend made me this banner and I can post it!
Btw. Add my spot ↓
www.fanpop.com/spot/sirenix-and-harmonix

Nope, that's why fanpop has he "image credit" thing