Levan,
The 'Rustavi International Motorpark.prj.xml ' is only used by the trackeditor.
The 'Rustavi International Motorpark.xml ' will be the input to trackgen.
Create a folder named 'Rustavi International Motorpark' under the category that the track should be in:
ie. D:\Games\torcs\tracks\road\Rustavi International Motorpark
Copy the 'Rustavi International Motorpark.xml ' file to that folder.
(I noticed inside the file that the category is set to 'Desktop') I don't know if it matters, but you might need to change it to 'Road'
now run trackgen -c road -n "'Rustavi International Motorpark" (NO EXTENSION). The folder and xml filename must match. (The trackgen -n argument is used for both, I think)
Track will be generated in the 'Rustavi International Motorpark' folder.
Not sure for Torcs, but with Speed-Dreams it would be available in the game at this point.
Cheers,
Joe