[list_item]If you are not already registered to iOS development Centre, then simply click on http://developer.apple.com/programs/ios [/list_item]
[list_item]You must have an Apple ID for the process to go forward. It costs $99/year if you’re in the United States, or £60/year for those in the UK.[/list_item]
VIDEO Guide on : How To Install NEW iOS 7 Beta 3 (FREE) Without A Dev Account Or UDID
if there is problem or you are unhappy with iOS 7 , you downgrade it to iOS 6 . here is video help with complete guide.