To enter the backrooms you have to No-Clip in The Frontrooms..

To No-Clip, you have to be very determined, and simply throw yourself into a wall Hoping you will No-Clip

and reach The Backrooms. While youre going against the wall, you will envision The Backrooms, and you will be able to see your first moments there as if your mind was warning you of what will happen if you do it. this will be  a sign that it will work this attempt. if you cant see your first moments while your going against the wall, that means it will not work in that attempt. if it doesnt work the first attempt, try it multiple tries. You will know it will work this time because as mentioned above you will envision The Backrooms in your first moments there as i your mind was warning ya. in this attempt, you will get through, and fall into Level 0. Congratulations, You No-Clipped Into The Backrooms. once you No-Clip into  The Backrooms, you will start off in Level 0, The first level of The Backrooms.

You can also No-Clip accidentally, for example if your walking across the street, trip and fall over, There is a 30% chance of No-Clip  Into The Backrooms. like the first method, youll start off in Level 0.

you can also Find a Entrance. Entrances are anomalies that happen in The Frontrooms or Reality in which you can No-Clip without doing anything special. For example, the method mentioned above, in which you fall into The Backrooms from the streets.  No-Clip Entrances can also take the form of Walls that are a shade darker than normal, Out of Place Doors, or even Liminal Spaces! However, to enter the backrooms you have to be prepared.

In The Backrooms there is something known as Backrooms radiation, which keeps the entities alive so you will

need a HAZMAT SUIT. Next, you have to be very sure of yourself and determined, and carry some weapons

to defend yourself of the entities. 
WEAPONS:

Silent Gun, knive, machete, sword, Antismiler radiation gun, any weapon that doesn’t make noise

so it doesn’t attract more entities as well as easy to hide and carry works.

FLASHLIGHT.

Some levels or areas within the levels are very dark, so you will need a FLASHLIGHT.

KEY OR 

FINAL WARNING;

DO NOT ENTER THE BACKROOMS IF YOU ARE/HAVE;

 

APEIROPHOBIA (FEAR OF INFINITY) CLAUSTROPHOBIA (LEVELS LIKE LEVEL 2 AND 3 ARE VERY CLAUSTROPHOBIC)

AUTOPHOBIA (LEVELS THAT ONLY HAS 1 ROOM AND YOUR LOCKED WITHIN IT

ISNT COMMON BUT CAN HAPPEN) BREATHING PROBLEMS SCHIZOPRENIA PRE-PHYSICAL INJURIES

(IN THE BACKROOMS YOURE GOING TO WALK AND RUN FOR A LONG TIME, NO MATTER WHICH LEVEL YOU ARE IN), So HIKING BOOTS are also necessary for survival.