Ideally, you cook macaroni and other pastas in boiling water on the stovetop. The website for Barilla's, the maker of Italian foods, has no mention of microwave cooking, and Mueller's, another pasta site, notes that only pasta specially made for microwaves should be cooked that way. However, necessity is the mother of invention, and sometimes the microwave is your only option. The taste may not be to Signor Barilla's liking, but it is possible to cook your elbow macaroni in the microwave.
Pour the water in the dish and boil the water in the microwave. Once it has reached a rolling boil, take the container out of the microwave and add salt. Let it dissolve.
Carefully add the pasta to the bowl and gently stir until it is saturated. Return the dish to the microwave.
Microwave on high for three minutes. Stir to keep the macaroni from sticking together, then cook for another three minutes.
Remove the dish from the microwave and put a cover or lid on it. Let it sit for 10 minutes.
Drain the macaroni. Rinse it only if you are making a pasta salad. It is ready to serve.