mando - i had no idea what i was doing. dont worry, you really cant screw up too bad as long as you dont do anything with the word "flash" and "rom" in it.
If all you want to do is theme your phone, my suggestion is following xweaponx's thread on how to setup a theme. You can dload all his theme files from his sig in the forums here. Then just learn how to apply his files into your phone (basically theme your phone with his theme) and you will learn the basics from there. And then, you will be off into the wonderful world of modding your mogul.
I am not smart, nor do I claim to be, when it comes to this stuff. Just tinkering and reading, thats all you can really do buddy. If you run into problems, people here are more than helpful, and can answer just about any question thrown out there.
And remember, no question is a stupid question