Blogger actually has a pretty simple interface once you remember to pay attention to all of the different tabs on the screen. Let me show you how I change my template and you'll see how to do it on your own blogger account too.

First, log in and get to your Dashboard. It'll look like this:

Click on the little machine wheel / cog icon (it's under "CHANGE SETTINGS") on the blog you'd like to change. The top of the subsequent screen will have the following set of tabs:

Click on "Template", and you'll see three options: Edit current, AdSense and Pick new. You want the third of these options (though the other two are worth checking out at some point too!):

There are lots of templates here: scroll down and see all your choices before you make a decision on what you'd like to use. I dug around and decided that Scribe was a good choice, so I clicked on "Use This Template" immediately below it:

You then get a warning:

I'm okay with this as I haven't made any changes to my existing template, so I click "OK" and my settings are successfully changed:

Almost done. Just click on "Republish" and watch the pretty spinning icon:

Before you know it, your weblog and all its individual pages will be magically rebuilt and your whole blog will look totally different!