Don't Fool Yourself! Looks Are Everything!

From the layout tab, just click on template designer link.  (see previous post) It's on the top right ish of the page.  Then you will get the above options:

Templates: Click on a style that you like and then from that, it allows you to have other choices.  See how the top right template is chosen and then linked to the templates below it?  Lots of choices!
Background:  Allows you to choose background color(if template allows) and a few other things but why worry about those details right now?
Adjust widths: Allows you to make columns on your blog bigger or smaller.  Also has a default choice just in case you goof it up.
Layout:  See below: too much to type up here!

As you can see above, the layout is how your blog will look.  This I think is important because if it looks good, people will stick around, read your blog and maybe even come back!  Choose one, try it for a week or so, then maybe change it and see what you think.  Remember then you can go back and add some gadgets.

Advanced:  Ok, it's just that, advanced!  Not really important in getting your blog up and running but something you can tinker with when you have spare time.  Or just leave it be!  Just allows you to have default fonts, background colors, text colors and such.  I'd just leave it at first.  I waited till just recently to mess with this stuff.