First off - plan of action for you
Go out and talk to 5 random strangers every day. They can be men or women, the check-out girl at the supermarket, the guy serving you your sandwich, whatever. Do it. Learn to just be social by smiling, asking people questions, telling them what's going on with your life, making a joke or two.
There is no magic line that is going to make a girl see your beautiful soul and instantly love you. If you cannot project your attractive qualities (which I'm sure you have) by conveying your identity with confidence, humour, intelligence, passion and articulateness, then she will not stick around to listen to you.
Plan of action for this situation - just fucking go up and talk to her. She obviously likes you, despite you being too much of a pussy to talk to her before. Maybe sit down next to her early on in the class, or catch her on her way out. Say hi, introduce yourself if she doesn't know you, and then instead of asking questions like "where are you from" say statements like "you're not from around here are you
" Have a story or two of something funny that happened to you recently in you back pocket. If the conversation runs out, just be like "oh so the most random thing happened..." and launch into it. Be flirty and fun, don't be afraid to tease (NOT insult) her a little, lightly touch her on the arm when you're making a joke or emphasising a point (DON'T look at where you're touching) and then tell her it was fun and discuss a time to meet again to continue the conversation over a coffee/drink. Then get her number.My 1 and Only Rule right now: DON'T BE A PUSSY.