The best and first place to start experimenting with art is drawing. Don't worry about focusing on realism, unless you want to. Sitting down with a pencil and a blank sheet of paper is exactly like making any art, only with less decision making up front. The magical thing about art is the total absence of any criteria. Here's this sheet of paper, and this pencil, and literally anything you choose to draw is totally acceptable and equivalent to anything else you might draw. So you have to start asking some pretty interesting questions to figure out what to do. Photography is also interesting and accessible for similar reasons.
Apart from that, I think just like with programming the best thing to do first is to start consuming the sort of thing you eventually want to make. If you aren't familiar with much art, it will be harder to understand the possibilities and decide what interests you. Get to a contemporary art museum, if there's one nearby, or go to the library and grab a book on contemporary art. If you arrive at any specific questions or want to find more art akin to something you find that you like, feel free to e-mail forrest@ the above URL.
The processing page has a nice gallery and also happens to be a very pleasant way to program this sort of thing: http://processing.org/exhibition/
Cant speak for painting but after a couple of failed attempts to pick up the guitar in my teens I one day started playing what I felt like instead of trying to play some fast hard rock riff, instant success and now I play guitar every day and starting to be genuinely good at it. So, paint what you feel like. Explore other painters and artists and try to copy their work while still maintaining your personal touch to it. Get a mentor or show what you do on some site for showing art, feedback is really important!
I have found, however, that while I really like photography and I really like coding, it can be very, very difficult to switch between the two - on the order of weeks to go from "thinking like a photographer" to "thinking like a programmer". Perhaps that will improve with time.