Well said, and I couldn't agree more. It seems to me there are a lot of folks flooding this forum, who just now got shiny new WordPress sites and want their blogs to look like something Jeff Zeldman himself created.
You have to take baby steps. Everyone was new at this once. I've been at it for many years now, and I learn something new every day, sometimes more often than that.
Being able to tweak your own site, to change your design up a bit is a great thing to be able to do. But not everyone is meant to do that. If you can't, and your site's design is important to you, then HIRE someone to do it for you. So that you can focus on writing, blogging or whatever compelled you to set up a WordPress blog/site in the first place.
If you want to learn web design, then don't continue to come on this forum posing those kind of basically off topic questions (as this forum is for WordPress issues, not design theory or CSS and HTML questions), but buy some books on CSS, HTML and design theory and read them. Practice on your own web site(s). Learn by doing. Same with PHP and MySQL. If you have web space, then it behooves you to understand the basics about it, and to understand how to take precautions to safeguard your server space and the data it contains.
Someone hold my drink while I climb down off my soapbox.
P.S. And did I miss something, or would there be a reason to have Google Adsense running on a 404 page?