Uggghhh I'm to young for this

So I'm 13 and I have a crush. Well, sort of. It's more of a "hey your cute, funny, attractive, nice, a good guy" he actually really is a good guy but he doesnt even know i exist🙄😂just like every other newbie teen. How do I flirt? I usually so quiet and shy (except around my friends, they think I'm crazy). Its so easy to talk to guys EXCEPT my crush. Maybe its because he's kinda popular? All the girls like him and I'm not sure what im feeling??? Please I need help. I want to learn how to talk to crushes.