Try growing up. Just in case you don't know, Y!A has a minimum age of 13!
read the other books in the series:
* Do you have certain magical rings?
* Have someone blow Susan's magical horn?
* Look for a portal in a cave or other special place.
Aslan has made several ways to get to Narnia.
Oh no! It is really hard to fin one of those, so your stuck here for now.
Fly on your broom!