I know there are some of you out there that always ask "oh no what DO i DO NEXT?!"
Slow down, think. A girl opened you, all you have to do is not be weird, don't talk too much, do not text too much...just text enough for the girl to say to herself "hm, maybe he isn't a creep like the rest of these thirsty dudes, hopefully he asks me out soon"
That is all you want to do. Get her number, create rapport, do what you need to do to make her see you as a safe dude to meet off the virtual world and you're in. Don't make it complicated. Take it from a seasoned online dater.