i met this girl at my friends house very brief. when i got home added her on facebook from there we have talked for a few days. however her responses to me are very short like ok cool or lol. than i saw her invited to my friends party on facebook and asked if she was going she responded with this answer

Her: nah...i have a lot of things to do.

i dont know if i did the right thing but wrote this back to her

Me : Enjoy yourself! Seeing how were both busy and you seem cool we should talk more another time. do you text or bbm? i promise ill only send you messages half the letter limit not the full

Do I give her time how can i get her to trust me to hang out and get her to talk more? she is definately an HB8 and want to persue.

I would be amazed if she answers back.
I think you are not in the hook point yet (the hints are the short replies) and therefore you are still in A2 so...
You came needy "we should talk more another time"... cuz you can't say something like this in A2 (this is not attractive).

hmmm I'm still a noob as you can see but I know the guidelines so as I see it if you're in A2 wait a couple of days and then say something C&F or maybe a neg you can also tell her a DHV story and use WH questions so the answer will not be "yes\no\maybe\lol".