The question is meaningless as asked. Is it your way of saying you want to give each author a subdirectory (site.com/author1, site.com/author2, etc.) or a subdomain (author1.site.com, author2.site.com, etc.)?
yes!
does that cost extra though?
Er, yes what? Do you need subdirectories or subdomains?
If you need subdirectories, all you need to do is to go to Options | Permalinks in your admin interface and create this (or similar) custom permalink structure:
/%author%/%year%/%monthnum%/%day%/%postname%/
This will give you URLs like
site.com/author1/2008/06/12/post-title
If you need subdomains, you can either create them manually and install a separate copy of WordPress on each subdomain or install a single copy of WordPress MU, which will handle subdomains for you (if your hosting setup allows it, that is).
See i wanted to have different pages for different subjects…
Like they login, and they can post on there page and not the homepage.
That can be accomplished by modifying your theme. You can exclude posts in certain categories from showing on the main page. Read up on The Loop:
http://codex.wordpress.org/The_Loop
