Why am I so envious of my friend?

I have this friend and it seems like no matter what girls always come to him. This girl in our class always messes with him and stuff and it got me thinking. Why can't I be like that. I constantly ask him how he does it. He gets girls without even trying. I never had the guts to just walk up to a girl and talk to her. Seeing someone do something I cant makes me depressed. I just don't have that level of confidence in myself. I'm not open to anybody besides my friends and it kills me on the inside because this low self esteem I have keeps me from being the person I know I can be. It's something about girls that me nervous. Then I don't know how to hold a conservation and I don't know how to be playful with girls. I think that I always overthink things therefore causing me to second guess myself. I need some good advice