Advice on my Parkour training?

[Masked Merlin]

I'm asking this twice, once under running and once here.

I'm 14, smaller than many kids my age, and out of shape. I'm not fat, but I'm not ripped. I've always been fascinated with Parkour, but don't know where to start. I've looked online to see what exercises and how many I should be doing, but I can't find a site that matches my age.

Here's what I'm doing now. (Don't laugh about my pullups, I am out of shape) I do three or four reps a day of the following.
15 (nonstop) pushups
30 (nonstop) situps
2 pullups (pause in between)

I also spend two hours swimming Monday, Wednesday, and Friday playing Water Polo.

I'm also not sure on what to eat. Fruits, veggies, breads?

Any feedback is helpful. I'm committed to this, I'll do anything within reason.