wow. That is a very complicated question. Usually you just believe. That is the first step. But I think I can help. Maybe. The key to believing seems to be to accept all of your doubts, and push them aside, similar to meditating. Instead of ignoring them, because in that case they would still be there, make sure to accept that you have them, but reassure yourself that they are groundless. If you remove doubts, you should just be left with only the will to do something, and the belief that it will work. Hope I helped. :)
The way you express your question is very vague.You want to learn a way to believe in magic?You want to find out what path you'll follow?Truly ,I can't figure out what you ask exactly so I can't give you an answer on all the possible questions you might have.