To get this achievement you must defeat certain bosses and light the bonfires that count as their area. Each one adds a light to the map in the mansion in Majula. Note: Do not kill Cale (He will be a target given by Royal Sorcerer Navlaan). Thanks to Thee Alec P for pointing this out.
Firstly, you must find Cale the Cartographer. He is found in the open area after the Cardinal Tower bonfire in the Forest of Fallen Giants. From the bonfire go down the ladder and out where the fog gate is/was. Go halfway up the tree then jump off to the right to land on a roof in the middle of the area. Then, going in the same direction as you were going up the tree (towards the mountain), jump across to another platform. From there go right and down towards a cave entrance which sits in the corner next to a wall.
You must exhaust his dialogue, and make sure that he gives you the Mansion Key.
Now that you have the key, go back to Majula and enter the mansion, which is the large building behind the pit. As you enter go right, follow this along and around a corner, then continue onwards through a doorway and down some stairs. You should be able to see the map on the ground. From the bottom of the stairs go down the next stairs to your right. There is a skeleton down here, kill it and then go back to the bonfire and rest.
Now you can proceed to light the flames. This is done by lighting certain bonfires and killing certain bosses, I will order them as you will likely come across them in the game:
1. Light the Cardinal Tower bonfire in the Forest of Fallen Giants, the kill the Last Giant.
2. Light The Saltfort bonfire in Sinner's Rise, then kill the Lost Sinner.
3. Light the Eygil's Idol bonfire in the Iron Keep, then kill the Old Iron King.
4. Light the Hidden Chamber bonfire in Black Gulch, then kill the Rotten.
5. Light the Lower Brightstone Cove bonfire in Brightstone Cove Tseldora, then kill the Duke's Dear Freja.
6. Light the Undead Ditch bonfire in the Undead Crypt, then obtain the King's Ring.
7. Light the Shrine Entrance bonfire in Dragon Shrine, then obtain the Ashen Mist Heart.
8. Light the King's Gate bonfire in Drangleic Castle, then kill Throne Watcher and Throne Defender (Changed from the original wherein you had to kill Nashandra).
Now that you have all of the flames lit, go back to the map in the mansion in Majula, and talk to Cale. He will gift you his gear and the achievement will pop.