Help me with approach on facebook with the girl I like !!!!?

[alberto]

Hi guys and girls,
A friend of mine showed me the profile a his former classmate, and since she's very pretty, I want to know here and maybe, approach her.
But there is a difficult, she seems to be a " forever alone girl " and I don't know how to start the communication with her. Help me !!!!
( We don't know each-other, and I can't meet her so facebook is the only method I have. )
Even if I poke her I won't have any advantages because in chat I don't know how to start the conversation D:
My friend was a former classmate in when they were in middle school and he don't have a good relationships with her.
When I said that I can't meet her, I was referring to the fact that we don't ave any common friend ( she's doesn't have any kind of relationship with the " outside world " :C ....