How to get a girls attention?

[beast-ya]

i am a girl
there are two possibilities that will happen if you do it.
first:
you might catch her attention, and she might ask if she know you, or she may say that she probably remember you, and both of you will start chatting

second:
she might think that you are just a man that going crazy about her since high school and she might feel scared or annoying.

second option:
just let her be
maybe she dont want to reply because she busy
or
she want to see your reaction whether you crazy about her
so the best thing i suggest,
dont comment on her picture, just let her waiting for you, (unless she is not interested)
maybe she will be wondering who you are and reply your message...