Instructions
Visit the Western Plaguelands. If you're the alliance, the easiest way to enter the Western Plagulands is by traveling through the Hinterlands and taking the dotted path to the northwest. The path leads up a steep hill and crosses the Western Plaguelands border. To enter the Hinterlands, you must take the tunnel from the Arathi Highlands. If you're the horde, go to the Undercity and run directly east. You'll run into the Western Plaguelands.
Run south of Chillwind Camp. If you're the alliance, run directly west to arrive at the camp. You'll pass a graveyard on your way. Once you arrive, take the southern road out of Chillwind Camp. If you're the horde, run south after you pass the Bulkwark and jump into the body of water. Swim to the other side and join together with the road. Do not stop at Chillwind Camp; it is alliance territory, and you may get killed. Continue running south to exit the Western Plaguelands.
Continue on the road until you reach Stahnbrad, which is part of the Alterac Mountains. Open your map once you see "You've discovered Stahnbrad" in the chat box. An area of the map should open up and reveal a mountainous range covered in snow. The Alterac Mountains make up the entire area plus a stretch of land to the south and west.