Hard to approach girl? Frustrated?

I see this HOT chick at the gym at same time every evening I go to the gym. One night, I was using a smith machine for squats. There are four smith machines altogether in a square format. This chick comes from behind me and wants to use the one I was facing. Unfortunately, some guy was already using it. The other two were unoccupied but she didnt use them. She wanted the one in front of me. When she approached from behind, she pulled her shorts a little (to get my attention?). I had wondered if this was a sign to talk to her or if I was looking too much into it. Anyway, I saw her again today, but it was crowded unlike last friday. I have no idea how to approach to her in the gym. She's obviously being crowded around guys because of how good looking she is. But again, I have no reason or idea how to approach her in the gym. It's got me frustrated and down because what if someone else gets to her before I do? All the negative stuff swells my brain when this happens. Any thoughts?