Help would be appreciated

[JustAGuy]

Hey guys, I'm very new to this forum. I was seeking for help, but didn't know who to talk to, and found this website. This looks like it will be a long post, but hang with me here. Well, there's this girl. To introduce her, she is my best friend's girlfriend's best friend. We hang out almost every weekend, and often seem to have a good time. I really like her and I want to get to know her. But it seems like she's got a couple guys hitting on her. There was a party last weekend and we were both there. Being the shy guy that I am, I didn't make a move. I didn't do anything. Right now, I'm hating myself for it. Instead, a guy was flirting with her, he had his arms around her, and she was leaned into him. From other people, I get a lot of compliments that I am a good looking guy, and so I should not have a problem. What can I do to make her want me, and boost my self confidence so I can engage in more activities or conversations with her? I don't think this girl doesn't like me, as when we meet eyes, it doesn't seem bad.