Well, it isn't that hard, really. Here are a few simple steps. Now, bear in mind it is the customization that is tough. If there is something you really need -- adsense, a special sort of widget on the side -- that's a different thing. Post a comment and I'll see what I can do.
So, go to this website: http://www.btemplates.com
You'll see on this page a fantastic list of just about any sort of template you may be interested in. They are listed by different colors, different layouts, and so on. Here's some of my favorites:
Notepad Chaos, my current template
Blogger Notes, another writerly template
Outdoorsy, a pretty nice looking blog
Now, you can download one of these and install them. Here's how: first, download the .zip file to your computer and open it up. Next, go to you blogger layout tab (found next to the create post button). Click there and you will get the layout manager. At the top, there are links. Click on Edit HTML.
At the top of the page will be an upload dialogue box. Click upload and surf to where you unzipped your file. Hit okay and okay. Your template is now applied and you want to save it. Don't worry. This process will not change any of your posts. It will only change how they look.
And that's basically it. The customization is the hard part. If the template you chose has a readme file, take a look at that. A good source of help with templates is the page you downloaded it from. There are comments at the bottom of the page that address potential bugs.
Your lay out screen is very helpful, too. You can add gadgets from there to increase your functionality -- like the followers gadget. If this all makes you nervous, you can create a new blog and practice in there. That way your blog has no downtime until you are ready to change over.
I know this is not as indepth as if can be because it is actually a very complex system. If anyone needs help, let me know. I'd be willing to set up templates for some free traffic. :) I only have five very dedicated and lovely followers, but I'd like more. :) Hope this helps someone out there!