mouse x and mouse y not set up,Mouse X and Mouse Y not setup

how do i set them up in unity 2019,i know this might sound like a dumb question but im new to unity. how do i set up mouse x and mouse y?

Are you already check the input manager?
try to look over there on Edit > Input Manager > then look Mouse X and Mouse Y name.
This is how to use :

float posMouseAxis = Input.GetAxis("Mouse X");

“Mouse X” is name of the name that i mentioned. or try to look over here:
Unity - Scripting API: Input.GetAxis

Hope it help.