How to make the next move?

K so I finally figured it's time I make the next step to ask this girl out because my friend has been trying to like flirt with her so I need to make a move to get a little further (which I know he's not gonna do cus he's to much of a pussy) so my question is should I ask for her number first then like ask her out later? How should I ask her out? I don't wanna do anything corny like pull her off to the side and be like ';I like you';, I want it to be kinda casual. I don't really know what to say cus I never asked a girl out or anything before. I don't even have her number should I ask for it first and if so how? Oh yeah I don't have a car so I don't know what to ask her to go do with me?