Though I'm an experienced programmer, unfortunately I just dabble with Mathematica and am struggling with some stuff I would have expected (as a programmer) to be trivial

(NB I did Google searches and even a session with ChatGPT but could not get an answer that worked)

Basically, I wrote a small financial analysis package for myself and decided to put the common function in a separate package (for reuse). The package has a .m extension and of course is bracketed with BeginPackage/EndPackage and the path to that package is in the search path for Mathematica.

My problem is that package does not seem to run automatically when it is needed. Specifically, if I don't explicitly open that package and click the Run Package button, then my main notebook that uses that package doesn't work.

How do I make that package be automatically available and ready for use?

Thanks in advance