how to display no all posts (only post from diferrent category than default)

hallo I have problem .Mayby you know how to solve it.I use WordPress 1.5 and Northern-Web-Coders thame.I wont to change default categories from “uncategorized” to other..in short: On a main page in WordPress there are shown all post from “uncategorized” category .I want only posts from category eg job..I don’t know how to do it (maybye in PHP but where). ??thank you for advice