Newb questions on making blog categories?

Using Drupal 6 on http://www.computerquestionhelp.com/ at the moment. I am currently using Path auto and customizing my url's per blog page that I write. What is the easiest way to categorize them and place my categories on my front page as a block? Does Drupal come with whatever I need to do this? Is there a module I can download for Drupal 6 that would make this easier? I'm assuming I will have to manually set a category to each blog I already have written. Is there something out there where I can select a category when creating a blog instead of making fake folders in my urls?

Thanks!