Help needed for DarkRp server to remember who bought a vehicle

Im making a community slowly. At the moment we have a gmod sandbox server and a Minecraft server.

Next server we would like is a DarkRp Server. Coded alot so far however I would like to have a function where once you buy a car from the f4 menu, the server remembers that you have bought one. Even after youy leave the server still has data that your steam id owns a car. So when a player rejoins he can respawn that car with no extra cost. I have googled for the past 2 hours with no luck on how this would be done. I do edits mainly and I am slowly learning. I know i would have to save the data to a text file but i do not know how to do all this. So if someone can help me with this I can also learn at the same time.

Regards
Adamski0811

Why did you make 2 threads?