There are three options available. Choosing the best one for you will depend on how much strength and movement you have in your arms. The first option is the most common one and is the one that is fitted to my car. If you need the second or third option, then I would have to teach you in your own car.
1. Use a steering ball with your left arm. The steering ball allows you to steer with one arm only, this will free up your right arm to operate a combined accelerator/brake/signal lever. You push the lever to brake, pull it to accelerate and flick the switch on top to signal. These controls allow you to brake and steer at the same time.
2. Use a ring accelerator and brake lever. The ring accelerator can be fitted either behind or in front of the steering wheel. Depending on type of ring you have fitted, it is either operated with your fingers and thumbs to push or pull it, or operated with your fingers to rotate it. When you want to brake, you take your right arm off the steering wheel and push the lever down. These controls do not allow you to brake and steer at the same time. They do allow you to steer with both arms, though. If you find it difficult to steer with a steering ball, because your left arm is weak, then these controls may be a better option.
3. Use an electric mini steering wheel, an electric gas/brake joystick, an electric handbrake and an electric gearstick. These controls have no mechanical connection to the car. The controls are electric and when you move them electric motors move the car’s controls. The mini steering wheel allows you to steer with your left arm using small movements. This will free up your right arm to operate the gas/brake joystick. You push it to brake using a small movement and pull it to accelerate using a small movement. A separate control panel allows you operate the handbrake, gearstick and other things on the car. These controls are expensive to buy and fit. They also require more changes to your car than the first two options. They only require small movements and a small amount of effort, though. If both of your arms are weak and you cannot steer using either of the two options above, then these controls may be the best option.