Adding popups via popup builder is very easy, to select a popup click on the Popups button in the bottom bar of the builder
Then the popups window will appear and you can choose which popup you want to add to you page
After adding a popup you can via the Popups button:
Open the popup by clicking on it.
access to its settings by click in settings icon.
Delete the popup.
You can also add new popups to your page!