Select Field that selects application

A little help please.
I have a form that I want to have a select field that selects from a list of applications I have stored in a table with a name URL for each app. What I want to achieve is with a record open in the first form, when a user selects an app, pass a variable from the first form to the selects app and open it with the associated records below the first form.
I am trying to use AJAX event on change to do this but have no idea what to put in the event except sc_redir. I can’t come up with all the syntax.
Also not sure if I have the URL’s correct. I have them in table as …/MyApp/MyApp.php

Many thanks.
Mark Stopkey