Begining UI Design

[gomer81]

I program in a few different languages and am self taught but alot of this ui stuff is really weird when I look at it. I know how to use the uibuilder and all but I was wondering if there was a good resource for learning how to make my own changes/pieces for example id like to start my making my own player piece with larger bars and % and health #'s. Im not asking for a how to but rather just where to start to learn this stuff (if a how-to for something similar exists then thats fine too I learn great from example as well)

Thanks alot.