One of the ways I try to debug and fine-tune my Blogger template (and see how other web-pages are constructed) is to view the page code of it and of other blogs I find well designed.
If you are using Firefox, it's pretty easy to do. Just right click on the page and select "View Page Source" You will get another window that will show you the HTML/XHTML code. (Tip: You can also manually change the settings for Firefox to use another external text editor instead.)
TechBlog co-blogger Jim Thompson recently tipped me off to an "advanced" extension for Firefox with a clever name. (Thanks Jim!)
For Internet Explorer
While I am a heavy Firefox user, I do use Internet Explorer (now v7) regularly. Imagine my surprise when I stumbled across a very similar tool for it over on the IEBlog site.
While still in beta, it has been stable on my systems. Like Firebug, it is a wonderful tool that helps you see what is going on behind the mysterious veil of web-page coding.
More information on it here on its Microsoft download page.
Even if you aren't a regular web-page coder, these are both good tools to have available on your browsers...just in case.