Post links 404 not found

Hi,
I would like to use WordPress 2.3.1 has a CMS.
What I have done yet:
Installed WP in /blog
– Copied index.php at the root of the server
– Created a page, called Home
– Set Home as the front page
– Created a page called News
– Set blog posts at News page
Most of what I want to do is working fine.
Since I have made these changes I have 404 not found when I click on post links in the News section.
I think I have to change path of these post links but I do not know how and where to make these changes. Are you able to help me?

Thank You
gjfo