How a girl can tell a guy she likes him?

That's a hard question! If you're friends with him and tell him that you like him, it will be awkward from then on if it doesn't go the way you want. If you really like this guy, do things to attract attention to yourself when he's around. If he pays a lot of attention to you, then maybe he feels the same way. Then you can let it be known that you like him and maybe then he'll let you know that he likes you. I'm sure that there are a lot of guys out there that you like that like you too. They may be feeling the same exact way you are.