HELP!

OK, all you bloggy people. I figured out how to get subscribe buttons thingies to show up. I figured out how to get blogs I follow to show up. What I can't figure out how to do is categorize my blog posts. Like, I'd like to have my archive divided up by subject, so if someone is looking for all sewing posts, they'd be in one list, etc.
Can someone walk me through? And do you have any other suggestions to improve the look and usability of this place? I would like it to function well.....but I'm not in a space where it feels like effort well spent to try to figure it out on my own right now.
So...help? Pretty please? It would be most appreciated.