Is walking good for me if I have fibromyalgia that results in shoulders cramps. And what is the range per week? I walk for two hours 3days a week.?

Keep exercising. You should keep exercising but instead walk 30 - 60 minutes daily. You will experience less muscle and joint fatigue but still get the same health benefits.
Great. That amount is great. If you are not have any other symptoms like leg pain or chest pain. You may want to try some stretching exercises. Consider a session with a personal trainer to get some pointers. Many people forget about the benefits of stretching and light weight training.