Niko, a .css isn't a layout, it's simply a style to keep the rest of the page uniform, like custom fonts and stuff via various tags. A .css file is 100% useless at creating a layout if you're just beginning, becuase implementing it will be so frustrating if you haven't learnt any HTML before hand. First you should learn HTML, create sites with it, then learn how to implement CSS into your pages after you've learnt HTML.
My personal editor of choice for HTML/CSS/<everything> is Coda (Mac only
), very useful if you have a mac, supports code highlighting for everything you can think of, HTML, CSS, and PHP manuals in the program, FTP Client, Browser, Terminal/SSH client (If you need to set up mySQL tables and stuff by command line, but that's a bit advanced). A bloody awesome program for Web Design for OSX.