How do I show her I'm interested?

So I'm a senior in high school and I kinda like this one girl that I met through my friend. The first time I saw her she was with my friend and they both said hi to me and I really didn't notice her at all. Then for the next few days if she saw me she would always say and and she honked at me twice when she saw me lol. A couple days after that we parked next to each other and she was sitting in her car and saw me and said hi when I was walking to my car. I started to talk to her for the first time and she asked me if I wanted to go out to eat with her friends (there was like 5 girls in the car) and I wanted to say yes but I only had 6 dollars on my card lol. The last time I saw her was about 2 weeks ago, the last day before a 2 week break of school. She was having some problems with her car so I brought my friend who knows a lot about cars to come over and help. He couldn't figure out what was wrong with it but when we left she told me thank you and that I was so sweet and then gave me a hug. Don't think we just left her there lol, her dad was coming. So I don't get a whole lot of chances to see her so how do I make a move/show her I'm interested?