I've already recolored the layers and I'm going to start by selecting the bottom layer and duplicating it. Select the new duplicated layer with your magic wand.
Now go to Select -> Modify -> Contract
The amount you enter here will be the width of the border. I'm going to use 20px.
Next, click on the "Refine Edge" box.
Set the "Smooth" bar to 2. This will eliminate jagged edges when we delete the rest of the layer.
Now hit delete, and the rest of the layer will disappear leaving just a border. I've added a glitter layer style to the new border layer.
I usually include a slight bevel to the glitter layer styles that I have for download. But if that isn't included, I'd suggest adding a small bevel to give the glitter a little depth.