If its a wordpress blog
1. Go to categories section and add your categories. Don't forget to add description to the categories. Google loves that. - The categories tab is on your left hand side.
2. Arrange your categories logically. Depending on the topic of your blog
3. When you post your article,don't forget to click on the category it will go to.
That is as much as I can tell from what you need. If you need more specifics just holler.
You can also use pages,but leave those for when you have more information to give eg about us,privacy policy(very important),terms,links to others etc
Jose: If I make it through this thug life, I'll see you one day. The Lord is the only way to stop the hurt.