Therefore it is necessary to have the GP2Nocd utility installed. If you already have skip the next lines. If not you have to extract the zip and copy the gp2nocd.exe into your game directory. Run this file and create a directory called "circuits" in your gp2 directory. Copy all the track.dat files (f1ct01.dat, f1ct02.dat, ... f1ct16.dat) from your Gp2 CD into the "circuits" directory. That's all. Now back to the track. 

All track zips contain at least one track.dat file. Most of them also have nice jams. They're mostly compressed into jad-files, which were extracted to jams with the convert.exe. This file is also included in any track zipped file. 

Have a look at the gp2form.txt (included in the zipped file). Somewhere there is a note that tells you in what directory the jam files must be. This directory must be created in the gamejams directory in your gp2 dir. Extract from the zipped file all the .jad files and the convert.exe into this directory. Run the convert.exe and all jads were converted automatically into jams. 

Copy the track.dat file of the zipped file into the circuits directory and rename it as one of the sixteen existing files (e.g. f1ct04.dat for slot 4). 

If you've done everything right it should work now.