The tutorials section on processing.org are really the best place to start whether you’re familiar with traditional programming concepts or not. They start out really simple and grow to extend functionality as you’re learning.
Once you’ve gone through three or four of those tutorials you should try to make something unique and absolutely post results to your tumblr. Once you’ve done that please be sure to tag them properly and if you let me know I’ll take a look at them directly and offer “free and cheap” criticisms. :)
As with just about everything, you’ll learn best by doing. Keep your ideas as small as possible at the start and you will have far fewer problems that seem insurmountable. If you have specific questions about how to do stuff I am positive that asking questions here on Tumblr would get you good results; check the #processing tag to find other folks using Processing, follow them, reblog their stuff (if you like it) and “get involved.”
Hope this helps, best of luck with the artcoding - it is probably the most fun you can have with a computer.