easy, in your profile under your images there is an uption in blue that says "upload photos" click in that and then upload the photo you want! down it says: "make this imagen my icon" or something like that, click in the little square and then click in "submit imagen" and tadah! you have that as an icon ;)
Very easy!Just click upload pictures on your profile. Then, look for the name of your icon. Then, check the box that say "make this picture my profile picture".Then, cick "upload picture". Then, wait for it upload. Then TADA! There it is!