Instructions
Visit Tranquillien in the middle of the map and slightly to the north. Tranquillien is a horde encampment. If you're the alliance, do not go inside of the camp or the guards will attack you.
Take the northern path through Tranquillien if you wish to enter Eversong Woods. Once you cross a bridge, you'll arrive in the Woods. Entering Eversong is only useful if you wish to visit Silvermoon City or have leftover quests in the zone. If you're the alliance, go around Tranquillien rather than through.
Follow the southern path if you wish to enter the Eastern Plaguelands. The path will lead you to a gate. Past the gate lies the Eastern Plaguelands. The zone is intended for level 40-plus players.
Go to Silvermoon City if you are a low level blood elf and want to leave the blood elf area altogether. Once you reach Silvermoon City, go to the Sunfury Spire at the northern edge of the city. Click on the red "Orb of Translocation" to go to the Undercity.