Select the Myths of the Eastern Realm tile, then New Game to begin playing.
If you cannot locate the Myths of the Eastern Realm tile, please make sure that the DLC is installed.
As you will play the DLC as a new character, you can begin Myths of the Eastern Realm, even if you have not completed the main game.
The DLC save files are separate from the main game saves. This means your progress in the main game will not be affected at all when you start the DLC.
If you have any other questions, please get in touch.