You can use the Connect Closed command to close open shapes or to connect and fill closed shapes. You can use Connect Closed with one or more objects.
On selected objects with open endpoints, the Connect Closed command draws a line between all endpoints, creating a completely closed shape.
On selected objects with no endpoints (already closed shapes), the Connect Closed command connects the objects and the resulting object is filled with the fill color of the first drawn object (the one in back). Note that in this case no lines are drawn.