How can i get over being shy around a boy?

Theres a boy named Dennis and I really like him and somehow he figured that out. My friend who i can always trust introduced me to him by jsut going over to him with me between cles and just said to him hi dennis this is my friend natali and he looked at me and i could feel my face getting red i said hi and he said hi back then i walked away. Well theres the fact that i really like him and i dont know if he likes me back but i cant stop being shy around him. the whole first time my friend introduced me to him i held my breath feeling like i wanted to stop and run away. I cant look at him with out him noticing and me looking away blushing like an idiot! HELP! how do i stop being so shy around him >.<