Steve Krug's book "Don't Make Me Think" is considered a classic amongst UX Designers. In the following four tutorials, we'll go through the least you can do today to make your website a lot more usable. It's a good way to jump into the field, and once done, you'll already feel like you can start making contributions to improve your site's UX.
If you want to dive deeper in UX Design, check out our UX Design List.