wpilib.screenstepslive.com is a fantastic resource with plenty of examples and guides on how to accomplish exactly this. If you have further questions feel free to ask! Good luck!
I definitely recommend checking out http://wpilib.screenstepslive.com/s/currentCS/m/java/l/145307-creating-your-benchtop-test-program. For an xbox controller, you will want to create a joystick object, motor controllers for the drive train, and a DifferentialDrive object. In teleopPeriodic(), you should create two double variables, one for each axis of the controller you want to use. Make the double equal to joystick.getRawAxis(axis), where the axis is the number of the axis you want to use. Then, add drivetrain.tankDrive(leftSpeed, rightSpeed). Let me know if you need any help!
You can check out our public github that has 2017 Steamworks code. That code base has lots of different functionality to it, you really only need to focus on the DriveTrain subsystem.
Also, there are other built-in WPI classes that will help, the DifferentialDrive being one of them.
Reach out for more help if you need, our team will be happy to help.