Wanting to build addons

[Johndo]

Hi, I've always loved getting the ui that I want but it's to the point now that I think I want to be making my own ui's. Been a fan of customization since Winamp broke out of their mold and had skins that were not rectangles anymore. I guess it's been too long now that I just sit back and wait for people to make stuff that I want. So I would like to know what do I need to learn to make addons?