I'm scared to tell a girl I like her what do I do?:(

That's OK. If you want, have a close friends of her be your bridge for friendship. While in friendship, study hard, be good anything you like: Be it sports, arts, debate etc.

Man, you are only 11 years old. This can wait.

Stop being scared, and tell her.

The longer you wait, the worse you will feel. Tell her and go from there. The worst she can do is say "no" and believe me, you will hear that more than you hear "yes"