As an example, create a simple scene with the following 3-node structure:
Node2D (or whatever you want as a root node)
Add a script to the root node
Wire the button's
pressed() signal to the script, containing the following code:
$ConfirmationDialog.visible = true
That's basically it. When the button is pressed, it's
pressed() fires, which calls the
_on_Button_pressed() function in the script. That function simply sets the visibility of the dialog to
true, which causes it to become visible.
Just season to taste...