No Categories on Wordpress

Hi
I just installed Wordpress on my site and created 3 categories for users to post in, but when I go to the main page, it just says "Nothing Found" with a search bar to search for posts. Well I know there aren't any posts yet because I just created it, but why aren't the categories showing up?
All I really wanted to do was have a page where people could post their lowcarb recipes to the site, but I can't figure out how to do that, so I installed this, and now I can't figure this out either.
So is there a way to get the categories that I created tro show up on the main page so people can post in them?

Thanks for your help.
Dan

From your description it looks like you need a forum, why did you install WordPress? Actually you can use WordPress to create a forum, but I'd suggest you to try something like phpBB before.