"Ah, that raises another question. By the way, I have no experience with blogs or launching live websites, so excuse these questions if they seem really ignorant."
No worries.
"If I were to pay for this blog service, to make it work I would also have to download software?"
My blog service will automatically install your choice of four different blogs. You will not need to do any downloading or configuring. Each of those four are listed on that page, and linked to their developer pages. So you can look at each of the four to see how they look and then tell me which one.
"Is there software available for free, or do you have to buy software?"
The software involved here is free to you, at a small cost to me. There are other programs other than the four I'll install for you, and you would be free to use them if you wanted, though I wouldn't be able to help you with those.
"Also, do you need anything else to make this work?"
Blogs these days are pretty simple. You don't need xml or html knowledge to figure it out. Posting is pretty straight forward, too. The one that I have come to prefer is wordpress, and its like writing a post on these forums. The difference is it let's you see the raw html if you want to.
You will probably find that some other tools will be helpful. For example, if you decide to become more advanced, you'll want to access the server files directly (outside the blog interface) and for that you'll need an FTP program. A good, free one, is filezilla. If you are new and just starting out, it could take you awhile before you needed to do that. The only exception is if you get really ambitious about your site designing- trying to go beyond what the blog software automatically have.