What Michael says is generally true. Tracks go into
Race07\Gamedata\Locations
However, just to complicate things, some tracks include menu items and these items go into
Race07\UIData
As Michael says too, people zip tracks with different amounts of directories included. You need to open the zip file and work out, from what directories are included, where to unzip.
1. If directories begin with the "trackname"\ - unzip into the Locations directory.
2. If directories begin with Gamedata\ and maybe UIData\ - unzip in the Race07 directory.