Once you finished Rakan's chapter, a tape will be on the floor next to the half painted wall (that leads you to the revolver). Grab the tape and put it into the VCR that is next to the TV. From the dining room, go down into the basement and continue straight along the path. If you see a flickering light you are on the right path. Go to the end of the hallway and grab the sledgehammer. Afterwards, all the lights will go out except for two. There are four brick walls you need to knock out with the sledgehammer. Move up to each one while moving your light bulbs. Once you knocked out the walls, grab the crate from one of the rooms. Move the crate to the hole where the little kid's bedroom is located. Interact with the crate and open the closet in the room. Easter egg found and achievement unlocked!
Here's a visual guide if thats easier for you:
*Credit goes to The Legion Smile for the video*
Just so you know, you don't have to use candles like they show in the video. You can move the light bulbs throughout the room to light your way.