Flirting is basically a collective name for small gestures that people make to show affection. This does not necessarily have to be romantic affection btw, but usually the more flirting (and the less subtle), the more romance is behind the motive.
You'll have to find your own style of flirting. What kind of flirting gestures do you like to use, without feeling forced or awkward? In the beginning, you will probably have to get outside your comfort zone to like any of these things, but you'll grow in it, I'm sure.
Examples of flirting behaviour:
- Giving compliments (for example, about a cloth or an accomplishment/decision she's made)
- Light touching (for example, a short touch on her forearm while you laugh at a joke)
- Teasing (there's a big difference between teasing and bullying; keep it playful)
- Make eye contact to intensify the power of the moment (don't stare, but make sure to focus on her and not the environment; I know it's difficult at first)
- Be honest with your non-verbal communication: laugh when she's funny - in your opinion, not hers, so it's a genuine laugh. But also for other emotions. Honesty is important because it shows whether you two match or not.
I think Dr. Nerdlove made a good video (and a bunch of written articles) about it:
https://www.youtube.com/watch?v=0aL3kCZN3X0