Go to The State Building located at Post Code 506 and apply for the tow truck job. From there you can go to Hayes Autos located at Post Code 155 to pick up your tow truck. With your tow truck you can provide tow service to other players and charge a reasonable fee to tow players vehicles anywhere those players like. You can also use your F1 work menu to toggle NPC to provide tow service to NPC players. Follow the GPS to the NPC vehicle and tow the NPC players vehicles back to Hayes Autos for repair. When you are finished working, return your tow truck and go inside Hayes Autos HQ to get your paycheck.