Open the game

Find the bed.
The difficult part starts here so I will help you find it quickly, you just have to look to the left or right, up or down (it varies depending on the version of the game you have, whether the normal or the GOTY edition)
Once you do you can find it +_+

Once you manage to find the bed you must press the E key
Remember that the "E" key is next to the "W" key which is next to the "Q" key

CURIOUS FACT!!!!!!!!!!!!!!!!!1!!

If you have purchased the collector's edition, you will have to press ctrl+shift+E on the keyboard that came with said edition, and you should also confirm by pressing the "Ñ" key twice

Sleep and enter that dream world where existential problems, loneliness, anguish leave that confusing, unstable, changing world in which interiority, instincts and intuitions predominate, along with the terror of contemplating that is not dead which can eternal lie, and in strange aeons you will find that even death may die.

Enjoy!:)