How to add a c++ library on ubuntu

  .so, c++, path, shared-libraries, ubuntu-20.04

I have downloaded a repository from github with a library with git clone
then I typed in terminal "make"
now I have a file in folder mylibrary/src

Now I want to run a c++ file which uses the library but I can’t compile it because of this error: "mylibrary.hpp: No such file or directory"

How to add it to PATH? yet I don’t understand what exactly I need to add
Whether it is folder "/home/mylibrary" or folder with the .so file

Source: Windows Questions C++