This is my first mockup design. I've created a4 magazine with easy to edit smart objects. You can replace cover, inside pages and background color.
I used render passes to create nice lighting at top of smart objects. Unfortunately they work best when they are in 32 bit depth. The only thing to do before saving in jpg format is to change mode to 8 bits/channel when your work is done. Merge the document and you are free to save in any format you want.
You can change background colour without loosing any light at top of it. Feel free to experiment with it and adjust it to match your design.