• It is very simple to install mods. First of all you need to download mod from here (or the other similar mods share website). Then copy your mod into Farming Simulator 2015 game folder. (C:\Users\PC_name\Documents\My Games\FarmingSimulator2015\Mods) Do not extract files, keep as it is in .zip format (modname.zip).
• What to do if you have .rar file. Then you need to extract file. It may be .exe or .zip files inside.

1. If it is .zip file just do as mentioned above (copy files to Farming Simulator 2015 game, under mods folder)
2. If it is .exe file double click file and it will install automaticlly.