The Intersect Tool is accessable in the Shapes Tab in the Vector Tools Panel in the Side Panel. It can be used to create a polygon with the overlapping area of two selected polygons, boxes, or circles in the Shapes Layer.
Before using the Intersect Tool, there must already be the two features in the Shapes Layer on which to base the intersect polygon. Features can be created using the Draw Tool, or added from other vector layers loaded onto the map.
To use the Intersect Tool, follow these steps:
Make sure that Shapes is selected in the Active Layer Selector in the Control Panel.
Select the two features on which to base the intersect polygon in the Shapes Layer.
Click the Intersect button in the Intersect Tool:
The created intersect feature is added to the Shapes Layer.