Error within Bubble Machine coding

Sorry, its the first time I am posting on this forum so I am unsure how it works..

Here is the error:

Arduino: 1.8.5 (Windows Store 1.8.10.0) (Windows 10), Board: "Arduino/Genuino Uno"

C:\Users\laure\Documents\Arduino\sketch_mar30a\sketch_mar30a.ino:1:21: fatal error: AFMotor.h: No such file or directory

 #include <AFMotor.h>

                     ^

compilation terminated.

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

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.