How to approach a girl that I like?

[Ignacio]

A girl I'm starting to like kinda, I wanted too see if she had Facebook and I found her, I added her, I liked and comment on her Profile Picture said ''Iuv your hair'' and she said ''thanks c:'' we both go to the same school but I only see her at lunch and Walking to class, also I catch her looking at me sometimes when we walk by eachother but that probably doesn't mean anything.
How can I approach this girl?
P.S: she also not a popular girl, I see her hangout with one friend that's it

[Allison]

Say hi

[Ryan]

Ignacio, You should probably message her on facebook, but don't rush into anything. Don't be to clingy. maybe you could ask her if you could sit by her and her friend. pay attention to what she says and what her friend says about her. Then maybe you could walk her to class. Become good friends with her, but don't become a brother to her.. good luck (: