You need to have Photoshop CS4+ version or Photoshop CC+ version for 3d mockups.Each file has different mockups – switch between them in the folders.
Find the “Change this” layer, click twice on the icon and a new window will open.
Insert your design in the window, save it and close.
Some scenes are also contains Clay version (or Changeable Color). That's a beautiful and popular clay stylisations. You can color device as you like.
Find "Change Color" layer and click on an icon, a Color Picker will be opened. Choose any color you like or add a gradient.
Sometimes we use 3d mockups instead of smart objects. That's gives a realistic view of your design in curved screens.
Find the 3d layer, under the‘Textures’ effect find ‘Change This’ and double click on it. Paste you design in opened window, close and save it.
If you have a Photoshop CC and upper version, but 3d is not working for you – make sure you graphic processor is turned on. Click CMD+K (Ctrl+K) and go to Performance tab. Make sure that checkbox under the Graphic Processor is turned on.
If the previous step didn't help, try resetting your Photoshop settings. To do this close Photoshop. Then press on Mac CMD+Control+Option and open it again. Message will pop up asking if you want to delete the Adobe Photoshop Settings file. Choose Yes.