Clearly it took a lot of balls for you to ask this question, so no, I'm not going to be condescending or rude...
Imagine them as if they're just your friends but also be flirty... (The friend thing is more for your comfortability and to help you get going.) I've got a very sarcastic and joke-y sense of humor, and I'm often getting girls' numbers, usually daily... I assume due to that and my looks... but here's the kicker with that... you don't have to be the most stunning man out there, either. An acquaintance I know married a super uggo dude, because he's got a fantastic personality. Sure there has to be the physical and the emotional attraction there, but the personality can become amplified and make you look even physically more attractive. Biology. Just have fun. Pretend they're your friend. Tease them, joke with them. It's unfortunately not something I can tell you via a forum, but just keep practicing! Most of all, be kind and be confident. Don't be cocky, don't be an asshole. Be kind, but don't be creepy. Be passionate about something (preferably a career or helping people or volunteering or something of that nature... Not something like "video games" or "anime". That'll just make them think you're weird.)
You got this! I'm sorry but I don't think a forum will help much. Especially one... like... this...
Try looking it up on youtube or something; They've got a tutorial for everything, I'm sure.