I've been using WordPress for a while now both for me and for my clients, but I am really interested in premium & free theme developments, it's something I would really love to learn how to do and am willing to dedicate my time to.
So first, what languages do I need to know?
My second question is, where can I go to really learn how to begin making themes, more of a course-like enviroment (videos, and the such) not just some loosely laced together blog posts about it. If you know of a book, I'm all for it and I'm willing to pay for some courses (not Lynda.com outragous yearly or monthly plans) .
Looking forward to your answers!