How do i flirt with a girl online on facebook?

[Victor]

(im talking about private messages, not im, or wall posts)
like i like her. i think she might like me im not sure. we have never talked on facebook, only in real life a lot. but the thing is im not sure if shes a frequest facebook uesr or what. i afraid i wont even get a reply back if i talk to her lol.
how do i "flirt" on facebook? like i dont know what to say to her to start a convo. we dont go to the same school (i graduated, she's younger then me), no same classes, only some same friends and hung out the other day and stuff like that. thats it.
should i talk about that? or start some random convo some how? what the hell do i say?
i need to find ways to flirt, i know how to flirt in real life, but not online like on facebook?
how do i do that? give me examples please? what do u do? does it work?
thanks.
i dont want to say something so werid that she doesn't even respond, that would kill me haha