I'm kickin myself now?

Last weekend my friends and I went out to the bar (mid 20's). I saw a girl there that I was very interested in meeting, however, regrettably I never made a move (I'm a shy guy). It appeared that this girl that I was interested in keep looking over at our group and my one acquaintance said I should make a move. I was the only one in our group not there "together" with someone. One of my friends recognized her and knew her name because he went to high school with the girl. (Maybe she was just looking over to see if she recognized him idk) My friend said they didn't really know each other well so they did not talk at the bar. Since he knew her name I found the girl that I wish I made a move on at the bar on Facebook. How weird would it be to message her via Facebook? Obviously, we're not Facebook friends and I think it would be pretty weird to do so. And if you do think it is worth messaging her via Facebook, what is the best not creepy way to do so and phrase it? Maybe I'll get lucky and run into this girl somewhere again which would be ideal to make a move. I know I'll actually do it this time since I'm kicking myself for not doing it in the first place. We do go to this bar fairly regularly and this is the first time I've ever see her there.