In the layers section there is a folder for each open and closed magazine sizes. Expand these folders by clicking the small down arrow. There are layers that are highlighted red. These are for adding your designs.
There are 4 magazine sizes:
A4 Portrait - 210mm x 297mm
A4 Landscape - 297mm x 210mm
US Portrait - 8.5in x 11in
US Landscape - 11in x 8.5in
To add your design:
1. Simply double click the thumbnail of the ‘Add Design Here’ layer
2. A new tab in Photoshop will open.
3. Go File > Place Linked and select your design.
4. Scale the design to fit (if needed).
5. Go File > Save. Close tab.