Need a little clarification. You uploaded the pic to your mobile pics album on facebook, and you want to know how to make that pic your profile picture?
Pretty sure he means how do you move a pic uploaded that is in Mobile Pics to the Profile Pics picture folder on Facebook..if that is his question, I don't know but he may want to ask Facebook support.
hit share in the gallery, choose facebook, when it asks you to add a caption before upload look up top and you'll see an option to choose mobile ablum. hope i helped!