You can use a simple array of strings to store the quest text, an array of booleans to tell if the quest has been completed and another array o booleans to tell if the player knows the quest. Use a enumerator or defines to srefer to the quests index in your code. Use a function to show and hide your GUI, that will also update your GUI and finally two labels, one for solved quests and another for known but not solved quests. This is just a suggestion on a simple system structure.