When registering, you will be asked for your "profile address". This is part of the URL that will be your profile page. For example, if you enter "clubber" (without the quotes), then your profile page will be located at:
Notice that you do NOT enter the entire URL, only the name at the end of your profile URL. Please note that you CANNOT change this once you have registered. So if you are a dancer and think you might be changing your stage name, you might want to use something else.