i am new on construct 2, and what i want to do is simple, but i have no idea how to do it

here is an exemple of what i want to do, to see the full picture

you have to play a melody to solve the puzzle

the melody order is : C+E+C+D

when the puzzle solved then a congratulation text appear

please help i really don't know what to do

here is the capx :

https://dl.dropboxusercontent.com/u/138507172/piano_puzzle.capx

thank you very much