dirtyharry50: The pokemon thing qualifies as a great romantic thing to do later on if all goes well. Little thoughtful surprises like that show you are fond of her and will make her feel special. Save that one for later though.
The most important thing is simply to just be yourself, the guy she already likes. I agree if she is playing footsie with you it seems pretty clear she likes you.
I think the park is a great idea. The next time you are speaking to each other in person, just come right out and ask her. Keep it simple. Just ask her if she'd like to go to the park together, mention things you could do there, etc. My guess is she will say yes.
If she does say yes, try to relax and just enjoy the time with her that day. Be yourself. Enjoy her company. At some point get your courage up and tell her you really like her and thank her for coming to the park with you. Beyond that, just enjoy the time talking to her as you normally would. It's okay to be shy sometimes. It always better to be your true self. If she likes you, she'll find that endearing about you. Don't worry over it.
Hopefully she says yes to a first date and all goes well. Be ready with a follow up. You might say something like, "It was fun being with you today. Want to <whatever next date idea you come up with here>? Maybe you could get together for some gaming fun, go out to eat, see a movie, etc. I'm sure you'll come up with something. :D