Write her a note asking do you wanna be my girlfriend ? Check yes or no or maybe so !! Or just hang with her and let things happen naturally :) your choice :)
I want to ask a girl to be my girlfriend but I don't know how she feels about me and I don't know how to ask her?( we're in high school now and I've known her since 8th grade) and I've never asked anyone out or been in a relationship.
A few conversations and a couple of dates should precede your proposal to be boyfriend and girlfriend. Just flat out asking her to be your girlfriend is immature and may scare her away.
You need to date this girl first before asking her to be your girlfriend. No offense, but I would be creeped out if a guy I never even dated just flat out asked me to be his girlfriend.
Dating lets you find out about a person. Some ask her out - group dates if you're under 16 and get to know her before you take that next leap.
You are dating this girl right? After you date for awhile you can discuss being exclusive, aka boyfriend/girlfriend.
Never ever EVER ask a girl to be your anything unless you are proposing, if things are going in the right direction then nothing really needs to be said