Ok, now for another tutorial where we apply the above technique to an actual template. I downloaded what is, right now, Suzy's most recent sketch. Here's what it looks like when unzipped. (I've adjusted the size of the photo so it's not much use to you--if you want the actual sketch as I got it as it's free, click here.)
You will also see that in your layers panel, every element of the layout is it's own layer. So now I'm going to start filling in the spots with pictures.