I was wondering a bunch of people have pictures of themselves on the profile i see the picture when people post threads and people in my friends list have pictures than their username next to it could someone please tell me how you do that?

If you mean avatar then you need to go to User CP (top left corner of the website) , and then edit avatar. Click browse and choose a picture you want and save changes.

Here you go.

Contact me if you require further assistance.