What is the “best” programming language to learn if you want to mockup your own ideas but don’t have a technical background?
I knew a very talented UX designer at Yahoo! who did all of his interactive mockups in PowerPoint—including widgets that you click to transition to another “page” in the interface. I’ve heard of people doing the same thing in Keynote, and OmniGraffle Pro also has tools for creating interactive mockups.
Other than that, you can’t go wrong with learning HTML and CSS—it’ll pay off many times over, and you can learn just enough jQuery to mock up some interactions.