MODDING NOOB!

Hey everyone,
I am a modding noob. I saw a mod of a computer case in a recent episode of the screen savers on techtv. I am hooked. I want to mod my computer. Where do I go? Where do I start? I wanna put all my things in a black case with a window on the side. I also want a color to cycle in the window. I saw a window with a light inside displaying the color blue, but I want mine to cycle through a few colors. If someone can help me out, I'd GREATLY appreciate it!