Unfortunately, what you’re asking right now is a *lot*. There’s a lot more to web design than “creating a cool website”. Many web designers have taken *years* to get where they are today (I’ve been doing it since 1992, and I’m still learning stuff.)
If you want to learn web design, this forum is most definitely not a place to ask for it – this is a place for people who need help in editing/altering/installing a single, specific blogging system – one of MANY. And what you’re asking – you haven’t even gotten *that* far yet – you’re jumping in the middle of things.
You need to Google for lessons in web design, basically. There are many free ones out there, for example, the w3cschools.com teaches some basics in HTML, XHTML, CSS and the like. Webmasterworld.com has some great forums where you can read up on semantics and the basics on everything from HTML to ASP and SEO. There are classes you can take in places like eclecticacademy.com or lvsonline.com. There are lists you can join that will provide more “one on one” information – just surf through Yahoo! groups – to name one place.
The scope of your question is indescribably *HUGE*. There’s no way you’re going to get the all-in-one answer you’re looking for on this one forum. This isn’t a question that can simply “just be answered” in a post. Sorry!