@crashmaster explained it already but if you still can't find the mods folder or for any reason still don't know then look here: http://wiki.beamng.com/Installing_Content It's the same method as on the forums but the difference is that you click on the zip icon instead of the orange button. In the steam directory? No that's not where it is supposed to be. Look at the link i gave in this post. Putting it in steam directory might delete it randomly or might mess with files.
