I am a complete noob so forgive me for asking..

I want to add a button to the end of a form so the user can add additional information in a pop up form. In this case the first form has event information. The sub form would have actions required for the particular event that was open at the time of the user pushing the button. The user can add multiple actions for one event. The actions are on a different table.

I am assuming this would require some Java which I have no experience in at all.

Thanks in advance to anyone kind enough to show me how to do this or maybe point to a pre-written script.

If your form is decomposed in parts, you can create differents bricks in the same layout.
It will create different sub-template files and you will be able to create easily some tabs.

BUT :
In your case, I think the best is to create 2 form layouts.
In the builder, Create a second template with a form brick inside.

Then, anywhere you want you can call the page for editing this extended form in popup.

For example in the grid :
Choose a column and from the column properties, create a link to your second form layout. Then also specify 'modal'.
This is not possible to 'link to layout' on special fields of tasks. Try on a simple string.

Hope it helps.