i have a b18 civic with civic compressor but i dont know what belt i should put on it
year make and model of the vehicle the belt is coming off

 

is the compressor mounted to the block already?

 

yea everything is all i eed is the belt to go charge it

 

as long as it bolts up and lines up, you've got the hard part done.
finding a belt should be easy.

get a rope and wrap it around the a/c and crank pulleys.
measure it at the lowest and highest points.
most parts numbers for belts have the length in the number.
you can also measure the belt when you go to the autoparts store.
start with the 2nd gen teg belt.