Many thanks for your message, and I'm pleased to hear as though you are now on the road to recovery.
The reason why a fracture is kept in plaster for 5-6 weeks is to immobile the bone(s) to allow for proper healing, however this does come at a cost to the other tissues. Long period of immobility often leads to joint and muscle stiffness leading to a loss in the available movement of the affected joint, as well as weakness of the wrist flexors and extensors.
The first aim would be to regain the available movement of the wrist so it is similar to the unaffected (left hand) and the first stage of your recovery would be through a gentle stretch / joint mobilising programme to restore range of movement. This wold involve bending turning the palm of your hand to face up and down as much as you can yourself and using your left hand to assist in moving the wrist further until a gentle stretch is held. Also, bending your wrist up towards you when your palm is facing both upwards and downwards, and again using your left hand to gradually increase the range of movement / stretch. You can start to strengthen your grip by squeezing a soft ball and holding for a few seconds before relaxing.
Once the movement of your right wrist is equal to that of the left wrist, we can start to strengthen the muscles by performing the same movements as above with the addition of light weights such as a tin of soup and start with a small number of repetitions and sets, allowing a day in between to rest.
Also do not forget that although your injury was related to your wrist, the whole arm would likely be used less so also exercises targeting the bicep muscles such as bending your elbow, or should exercises such as lifting your arm straight in front and out to the side of you with a small weight and some shoulder shrugs will ensure the rest of the 'chain' remains strong.
Lastly, start to use your arm functionally day to day however avoid carrying significant weight with your right hand only in the initial stages.
These exercises, as found on Guys and St Thomas' NHS Trust, are an excellent starting point. Click
here.
I hope this helps and let me know how you get on
Matt