From the introduction:
Dungeons & Dragons: Red Dragon’s Tale is an adventure that accompanies the LEGO® Ideas set of the same name. To play this adventure, you need one person to be the Dungeon Master and up to four other people to play the heroes, referred to hereafter as the Player Characters. Together, you build the LEGO Ideas set as you play through the adventure.
If you’re the Dungeon Master, read the boxed text in the “About the Heroes” section to the other players, then review the “Running the Adventure” section.
If you’re not the Dungeon Master, choose a Player Character from the options listed in the table below. Each Player Character comes with a LEGO minifigure, several minifigure accessories, and a Character Sheet that provides more information about the character.