Where is the method that controls saving items?

Alright, it's been a substantial amount of time since I've developed much in Joomla and I'm kind of diving back in after some time off.

For examples sake I have created a component for Widgets.

When I click to Create New widget - the form opens up with some of my set options "size, price, description" etc.

It works fine in that it creates that Widget in the database. But lets say
I wanted to have it save to another remote database elsewhere also when
the user clicks 'save & close'.

What files would I modify? How do I control what happens when the user clicks 'Save & Close'
and the form is submitted/posted?

I created my widget component using the component-creator online and it adheres to MVC architecture -
but it's been so long since I have played around with all this I'm kind
of re-learning.