How do I talk to a girl online?

[Dsd]

So yeah she's a famous guy's sister but she isn't a b. I added her on facebook but i dont think she remembers who I am because weve only seen each other twice or thrice. I really like her though. I wanna talk to her but whenever shes online i think twice and wuss out.

I dont really know if I should say hi or anything. What should I say next after hi and she replies? Step by step?
what? wouldnt be saying "you okay" be kinda awkward? lets pretend she doesnt know me cause she forgot who i was.

[Chrissi.xo]

* hey
*you okaay?
*you been up to much lately?
*do you want to meet up sometime soon?
*your really pretty..

and so on