From my good friend D.W. So easy and good for you.
Place salmon in a large non-stick skillet. Cut up salmon if you need to make it fit. Pour orange juice over salmon until it is mostly covered. It doesn't have to be completely submerged. In fact, seeing a little of the salmon helps you to know when it is done. Cook on medium high heat until it simmers. Cook for 2-5 minutes depending on thickness and size of salmon pieces, longer if it is thick. Turn and cook another 2-5 minutes. Do not overcook. Cook until it just starts to flake. It is better to under cook it than overcook and be dry. If it is under cooked you can always put it back into the pan and cook a little longer. It can be rare in the middle. Medium rare is optimal.
Once it is cooked, (hopefully not overcooked :) ) remove from pan and place on warmed plate or platter. Turn the burner to high and reduce the orange juice to desired thickness. If you reduce it too much and it is too thick, slowly add more orange while stirring. If you need more sauce, add more orange juice and reduce.
Serve reduced orange sauce over salmon.
And yes I have overcooked my salmon and over-reduced my orange juice. Why do you think I am so knowledgeable on the subject?