ok here are the steps of my problem

1:I made a box and put the measurement that i wanted it too be

2:i made the map modle editbal mesh

3:i selcted all the sides just like the tutorial showed me

4:i flipped it when clicked the flip button,but it dindnt flip like the tutorial did,it just made the all sides black.

there thats the best way i can tell you guys so plz help me or something

also there was some who helped me,he told me check the backfacing cull sqare.But when i checked it and fliped it it just made the sides invisible.

i just want to make a simple map plz!

You are using max 9.
rightclik the object and go object properties, then toggle backface cull.