1)

Click the floating plus icon in the lower right of a folder

2)

Enter a name for this tooltip

Add a URL rule where you want to place the tooltip 

3)

Select "Power HTML"

4)

To make it work, we have to select an HTML field

5)

Enter the message you want to be displayed in the empty field

Click on "Save"

6)

Publish this tooltip and it's respective parent folders

7)

You will see that the empty HTML field will now display the message you provided

8)

Here is the tooltip in action

9) Preview

10)

Select "Tooltip Guide"