Short story, met this nice girl a couple weeks ago, got her on facebook, have talked to her a little bit here and there for the past couple weeks. Asked her to come with me somewhere this weekend and she said she wanted to, but didnt hear back from her before the weekend because I only have her on facebook. She posted on my wall today, "sorry I couldn't come this weekend, I had to work. I hope you had fun

". She has a boyfriend that lives far away, but I want to escalate and get her number on facebook and take her on a date (I really like this girl). How should i approach on facebook to get number and escalate to date? Thanks in advance