Click on "Automaton" and "Add Automation" from the main screen. Decide what will cause the automation from the drop down menu in green.
"If This Happens" column list your trigger
Select and Name your Automation and Description
Decide what should happen when the automation is triggered. The result is called the Action.
Use the drop-down menus to select the action in the "Do This Action"
Select the Action to close the Water Main Shut off when water is detected. Then Click on "Save Changes" in bottom right hand corner.
Then you will see the Automation in your home screen.