Yesterday I told the boy I like that I like him and hes not acting any different? Its like he doesn't even know.. What do I do? Did I do something wrong?

No you did nothing wrong, you brave in my opinion. It takes alot of courage to tell someone you like them and the result can either be good or bad but the main point is that you've expressed your true feelings to him/her. He might not react because his unsure of himself and that you should wait for his answer. Goodluck