As drug courier the goal is to transport the drugs from the factory in San Fierro to different spots in Los Santos. The vehicle used to transport this is the Sanchez.
The bikes will be ready and waiting for you at the drugs factory.
To get to the factory use /gps - San Fierro - Drugs Factory.
This job has a high payout and can be done with 2 players, this will give the same payout for both and you will both receive some Reputation Points.