Creating my own skin

Hi everybody, I've started using xWiki a few weeks ago and now I want to make it look the way I want. So I'm trying to create my own skin. I read the Admin guide<http://www.xwiki.org/xwiki/bin/view/AdminGuide/Skins>about it, plus other mails but I have to say it's not an easy task. I don't really know where to start because I don't understand all the css files. xwiki10b1 has 23 css files but I think only 11 are used. Am I right ( style.css; elements.css; classes.css; xwiki.css; wiki.css; page.css; rss.css; screenlayout.css; microformats.css; presentation.css; colorsblack.css;) ? If yes, what are the other ones used for (chw.css, colorsblue.css, customcoloes.css, style1.css...) ? Why is page.css empty, is it the one to fill ? In other words, which css should I change if I want another layout, another font, colours.... Thanks for you help, Antonio