Another method of finding the ShopSim folder is going to the Windows Start Menu and typing %appdata% (with the percent signs). For me this pops open the Folder C:\Users\(MyUserName)\AppData\Roaming. Of course I want to look in Local, not Roaming, so I have to go up one level to just AppData, then go into Local, then ShopSim.
I assumed this folder was created upon startup, but you're not the first one unable to find it, so it may only be created upon saving the game.
Also, I'm using Windows 10. I believe the AppData folders are handled the same way in Windows 7 and 8, but I can't tell you that for certain. Hope this helps!