It depends what kind of barley you got
Pearled barley is the must refined, Hulled barley is the most unrefined.
For both, place 3 cups water to 1 cup barley in heavy pot. Cover and bring to boil. REduce heat to low.
Pearled - simmer 55 minutes, hulled - simmer 1 hour 45 minutes.
If you are not sure what kind you have, just check it after 55 minutes, if it is still hard and there is still water, keep cooking until tender.