Library Importing

:frowning:
i was using some code that controled an LCD, but i needed LiquidCrystal,
i succesfully got liquidcrystal but now i get the error:

C:\Users\USERNAME\Documents\Arduino\sketch_sep09a\sketch_sep09a.ino:20:31: fatal error: LiquidCrystal_I2C.h: No such file or directory

 #include <LiquidCrystal_I2C.h>

                               ^

compilation terminated.

exit status 1
Error compiling for board Arduino/Genuino Uno.

and i had typed the #include <LiquidCrystal_I2C.h> and i got the error again!

I
NEED
HELP

im using windows 10, i found the code for the arduino here:https://www.sunfounder.com/learn/RFID_kit_V1_for_Arduino/lesson-15-water-level-sensor-rfid-v1-0-for-arduino.html