htaccess help

[mh_and]

Hello guys,

I've been writing php for already a month and finally have my first ever site ready to be online.. it was really really hard for me but i made it with a lot of reading from this and other forums and tutorials.

Now I need to make my URLs nicer, so if you can help me, please do that

the structure I have is

domain.com/index.php - homepage
domain.com/post.php?cat=X - category page
domain.com/post.php?cat=X&post=Y - article page.

So I'd love to see my site

1. domain.com/Index.php redirected to root domain.com/
2. all pages to be with www
3. all .php extensions to root /
now the important part, I don't even know if it's possible

The category page should be rewrote to www.domain.com/post/CategoryName/
The post page should be rewrote to www.domain.com/post/CategoryName/PostName

This "Names"-s can be titles which are already applied... or how can i do this? Some field in database?

I'm absolutely unaware of this and this regular expressions aren't that easy for me so little explanations are also very appreciated. If i missed any needed info, just tell me and it'll be right up here..

Thanks.