Im (slowly

) learning how to use Xcode to make iPhone apps. So far i have a very simple one i want to test on my Phone, but when i connect it and change the Device from iPhone Simulator to iOS Device i get the error 'Code Sign error: The identity 'iPhone Developer' doesn't match any valid certificate/private key pair in the default keychain'
According to what i can find on google that means i'm not a registered developer, how do i become a developer (i know there's a charge involved), and is there any special steps i need to take?