how do I put up specific searchable content 4 user

Okay, this is a difficult question to explain, so I'll try my best:

I have a sports community website that I'm building for athletes and I'm wondering how I can have them select their favorite sports when they sign up (changable once registered) and then (big question) allow users to search by this criteria to find other users who are interested in the same sports as them?
Is there an extension to do this or something within community builder?

If anyone can please help me by explaining how to do this that'd be fantastic! Thank you so much! (This is my first community site)

Thanks again!

Multiselectfield for sports and advanced search component (search this site) for searching.

mikko

Thank you for replying so quickly, and this may sound stupid; but how do I go about doing a multiselect field? And then you say I can find the advanced search extension on this site? I've looked, but I'll look again.
Please inform on the mulitselect fields. Thank so much!

Just like creatign any other field

mikko