Changing your sex is a long, difficult, and expensive emotional and medical process. If you honestly feel you were born the wrong sex, then the years it takes to make the conversion happen will be worth it. There isn't a fast, easy spell to do it for you.
I'm assuming you're a teenager, and this is really something you need to talk to your parents about. Hopefully, your understanding parents will connect you with a supportive counsellor who will be able to guide you on the ins and outs about how to go about doing this.
Always be wary of online support groups - I recommend teenagers not using them. Best of luck!