World of Warcraft Alliance levels 10 to 20 Dungeon and Battlegrounds

After level 10, preferably between levels 15 and 18, go to Westfall. From there make your way southwest to Moonbrook. Head towards the Deadmines. You will find a building that you must enter to find the entrance to the mines.

If you are landing in Stormwind from the Elven island, make your way through Stormwind city and exit the front gates:

Stormwind

 

Then make your way through Elwynn Forest to Westfall following a path like this:

Elwynn Forest

 

Once in Westfall, follow this path to get to Moonbrook:
Deadmines Location

 

This is what you'll see when you get to Moonbrook:
Moonbrook

Once you get to Moonbrook head to the back of the town until you find this building. Enter through the door and go left, then up the stairs.
Mines Building

At the top of the stairs you'll find this entrance. Go in there and turn left, head down until you find the entrance to the mines.
Inside Building to the Mines

Once you find the secret entrance to the mines you will need to find the entrance to the actual dungeon. Follow the path to this place to enter the actual Deadmines Dungeon!
Deadmines Dungeon Entrance

 

Going to Stormwind City and entering the Stormwind Keep is where you will find the battle masters. They are the ones who can get you into the Battlegrounds!
Battlegrounds