Just follow through with the story. At the part where Freddy asks whether you want to listen to their music, tap Y or N on your keyboard. Five Easter eggs in this, click on the animatronics to find them!
All audio downloaded from YouTube. All images found on Google Images. All rights go to Scott Cawthon. "Five Nights At Freddy's 1 Song" by The Living Tombstone. Check it out here: https://www.youtube.com/watch?v=l18A5BOTlzE "Nine In The Afternoon" by Panic! At The Disco. Check it out here: https://www.youtube.com/watch?v=yCto3PCn8wo