How to call a php helper function from a form in, a joomla module?

Pardon me first for being a beginner in php and in joomla development (hello @mickmackusa!). I am creating a module which uses a form to first load users then on submit would display order items ordered by a client selected from the form. I have both parts of the question almost solved, that is, the list of users being displayed and data retrieved from the database if I select one user but I can do this separately. My question is: in my helper file, I have 2 functions for retrieving users (getUsers) and for retrieving client data (getDetails). The only issue I have is: how to set the form's action to call my getDetails function in my module's template file? I have tried

<form id="myform" method="post" action="getDetails()"> which does not work.

I have also tried

<form id="myform" method="post" action="<?php echo getDetails();?>">

which does not work either as I get a 404 error.

I guess I'm missing a basic thing here but could not find any answer.

Thanks to help me to get this to work.

source https://stackoverflow.com/questions/76203274/how-to-call-a-php-helper-function-from-a-form-in-a-joomla-module