GIMP :: Copy / Paste And Move A Selection?

I'm a longtime Photoshop user in the process of switching to Gimp. I've successfully used Gimp for very simple things like brightness/contrast, color adjustment, and sharpening of single-layer images. What I'm trying to do now involves creating a copy of the background and placing it next to the background image, and I can't figure out how to make it work.

Here's what I'm doing:

1. Resize the canvas to twice the width of the original image, leaving the original image at left. This creates a "blank" area to the right which displays as a checkerboard pattern.

2. The area of the original image is already selected (i.e., it already has a frame around it), so I copy and paste it. This creates a floating selection, duly noted in the list of layers.

3. But when I try to move the floating selection to position it to the right of the original image, in the blank area, it appears to disappear behind the checkerboard pattern.