Select a screen and custom tab from the list.
Then enter the Widget Title and optionally enter a Height. Note the size of the custom tab is usually more generous than the widget depending on the layout you have chosen for your overview. So please consider the overview layout you are selecting, for example Single Wide, Double Wide, etc., as well as the height of the widget. You can specify a height up to a maximum of 600 pixels for the widget to accommodate the URL. The minimum and default height of the widget is 300 pixels.