Gnjilane is a city in eastern Kosovo.
There are buses leaving from Pristina to Gnjilane every 20 minutes for about 2 euros one way, from Ferizaj/Uroševac there are bus connections about every 30 minutes. One can travel from Bujanovac to Gnjilane by bus though but the schedules can be unrealiable.
When visiting the Monastery note that while not strictly expected it is considered traditional to bring the monks juice, honey, or vegetable oil though some other foodstuffs from your home country will be greatly appreciated as well. These supplies are used to feed other visitors. If attending services do keep in mind that modest clothing is recommended, covered legs and shoulders are expected of both genders.