where to place callouts

[Wolfgang Engelmann]

There is a program callouts

https://www.ctan.org/pkg/callouts
The pack­age en­ables to de­fine the an­no­ta­tion en­vi­ron­ment, in 
which call­outs, notes, ar­rows, and the like can be placed to de­scribe 
cer­tain parts of a pic­ture.

It contains callouts.sty and callouts.tex.

Where should I place it in my Debian tree structure in order to use it 
under lyx?

Wolfgang