Step 1: Select “Your Design”

Double click the layer “Your Design”. This opens the smart object with the designs inside.

Show the “Placement Guide” and hide layer “Replace Me”.

Change Artwork 1

 

 

Step 2: Add your artwork

Place your design into the mockup by clicking File > Place Embedded. 
(You can also copy-paste artwork from another Photoshop window. Just click Select > All, and then click Edit > Copy)

Position your artwork and hit enter.

Change Artwork 3

 

Step 3: Hide “Placement Guide” + Save

Hide the placement guide, then click save. You can close the “Your Design” tab now.

Change Artwork 4

 

That’s it! Have fun :).