I hate error messages.
I think I've figured out how to do what I was asking about in this post (but it may be that I've just fudged it and made it a lot more complicated than it needed to be... I don't know). At the moment, I've got it running on a test site. The graphics and everything are working the way I want them to... but I'm having problems with the basics! Where the date and blog title should be, it says "Undefined". The little bit at the end of each post that says "Posted by" is missing, too (even though I've looked at the gadget and the correct box is checked... so I don't know what the problem is). And on top of everything else, Blogger is putting my name on the top of each post!
I used the Rounders 4 template as a base because it was the closest to what I was looking for. I don't know if that's what's screwed things up, but I couldn't even get those dates and post titles to show up with Minima, which is what I usually use. Something's messed up.
I tried to teach myself DHTML years ago, but the CSS part always confused me. Unfortunately, that's what Blogger uses, so that's what I need to figure out. The trouble is finding things like your sidebar in all that code... You can't just search for the text that's in your sidebar, because that's not part of the template. So you have to know exactly what you're looking for in order to fix it. Unfortunately... I don't.
This ladybug is going a bit cross-eyed. It's time to take a break from this. But if anyone has any suggestions for solving these problems, I'm listening!