There is no program named IEBCOMPARE. You may mean IEBCOMPR. The mechanics of specifying a SYSIN dataset to a job step specified in a JCL catalogged procedure are discussed in the JCL manuals.
This link points to the JCL User's Guide,
this link points to the JCL Reference,
this link points to the manual that describes the IEBCOMPR utility. If you encounter issues you do not understand while reading these manuals, and they can be difficult to understand, we can try to answer specific questions, though I doubt you will find many true experts for the IEBCOMPR utility lurking on this forum. We are not well equipped here to provide tutorials.
Just a personal opinion here: the controls provided in the IEBCOMPR SYSIN dataset are limited and are rarely used.