From the Manual

Create a New Document

• Open a template (File > Open) from the downloads.
• Press Ctrl N (Mac: Cmd N) to create a new document.
• In the dialog box, name the document using the same naming convention but with a different size reference. Set the size of the new document (doubling the width) and click OK.

Set a Guide

• In the Menu Bar choose View > New Guide.
• In the dialog box, set the Orientation to Vertical and the Position to half of the document width.
• Click OK.

Transfer the Layers

• Activate the original template.
• In the Layers panel, click on the layer directly above the Background layer to activate it.
• Holding down the Shift key, click on the top layer in the Layers panel.
• All layer should be active except the Background layer.
• Get the Move tool.
• On the document, hold down the Shift key and click and drag the clipping masks and journaling lines to the new document.
• In the Layers panel, click on one of the layers to activate it all by itself.

Edit the individual layers using the instructions from the last video.

If you can't see the edges of a bounding box, press Ctrl 0 (Mac: Cmd 0).

From the Transcript

The templates in this class are offered as 10 x 8 pages. If you’d like to work in a different size of template, this video will show you how to adapt.

Begin in Photoshop or Photoshop Elements by opening a document that you want to change to a different size. I'll be using template number nine. Then press Ctrl N, that's Cmd N on a Mac, to create a new document. In the new document dialog box I'll want to begin by naming this template very similar to the name of the original templates that I was given. But instead of the 10x8 size, this time I will enter 8x8 and I'll use the same document number. Next I'll set the Height of my document. I want my document to be an 8x8 page, so the Height is going to be eight. Now the Width is going to be double that, because there's two 8x8 pages sitting side-by-side. So the Width would need to be 16. Then, click OK. 

With the new document open, the next thing I need to do is to set a guide right in the center of the page that indicates the gutter. To do that, in the Menu Bar choose View > New Guide. In the dialog box, set the Orientation to Vertical and the Position needs to be halfway across the page, which in this case is at the 8-inch mark. Then, click OK.

Next, I'll return to the original 10x8 template. And in the Layers panel I'm going to click on the layer directly above the Background layer to activate it. Then scroll to the very top of the layers panel and holding down the shift key click on the very top layer. Now all the layers in the layers panel except for the background layer should be active. Get the Move tool and then click on the document and drag all of those layers into the new document, before you let go of the mouse though, press and hold the Shift key so that they'll land right in the center. Then go into the Layers panel and click on one of the layers to activate it all by itself. 

Now I can edit any of these shapes on the document I'll start with this shape over here on the left. Hold down the Ctrl or Cmd key and click on a shape that you want to activate. Then to transform that shape, get the Transform options by pressing Ctrl T, Cmd T on a Mac. If you can't see the edge of the bounding box, press Ctrl 0 or Cmd 0 on a Mac, then click and drag from any of the side handles of the bounding box to resize the shape. That shape looks good to me, so I'll click the checkmark to commit. Now I'm going work on this shape all the way over here on the right.

Again holding down the Ctrl or Cmd key, click on that shape to activate it in the Layers panel. And this particular one I'm just going to delete it. So I'll click on the Trash icon. Next I'll want to work on this next shape. So I'll press again the Ctrl or Cmd key, click on the shape, then get the Transform options and drag the shape to resize it. Click the checkmark to commit. Then I'll also change the size of the shape so that it matches the one above it. When finished, make sure to save the template as a layered PSD file into a folder that's located close to the folder that contains the original templates. So that's how to adjust the templates to a different size.