Think about it like this. When you design a website, you most likely want the pages to have a similar look. For example, on amiga.org you've got a mostly blue and white theme, certain fonts, etc.... If you design a page with just HTML, you have to write that you want those style settings on every page. With CSS, you can instead save these style settings in one file, and say 'use this style' by linking to this one file.
Think of it like a style template. Time is saved by only needing to write out the style settings once. I hope that makes sense.
PHP is also worth understanding too, if you want a fuller picture of how websites are put together, but one thing at a time. :-)
Gotta be honest, I don't like things all having the same look (that's why my site is erm... a wee bit different as some folk have said) plus all I have to do is point and click and type some text, pics $ music to create mine...
I couldn't be bothered learning HTML and all that malarky to I picked a point and click thingy that cuts out all that stuff, lazy, yup, but a lot less hassle than learning HTML...
