MX Simulator

I don't have photoshop yet so I downloaded gimp. I can edit the gear but I have problems putting it into the game even when I follow tutorials. I'm not sure if I'm doing something wrong or its the app. Can someone help me?

Just a guess but one thing in recent versions of GIMP is you have to use "export" so save a PNG now. If you use "save" you get an XCF file which the game won't understand.