Run a function inside functions.php

i have a form designed so when i click on submit button i want that the specific data in the form be sent to function defined inside functions.php…how do i call the function using pinegrow? …normal php i know how to do it…but using pinegrow how to run the function with the data?

I think this is done in the action property of the form tag.


But no further idea. Maybe a startpoint for you to search the web …