What @CubeAce says is entirely correct. Because these are user to user forums no-one who posts here can help you directly. You need to contact whoever you bought the software from.
However, one question: did you buy the software new or is the product actually second-hand, i.e. you bought it from someone who previously owned and used it? If so, you need to ask that person to contact Magix and ask that his registration of the software be cancelled, thus allowing you to register it.