Combining shapes to create a fill area

[Helen]

How do you combine two shapes, drawn using the freehand tool, and then combine them to create a fill area

The effect I'm after is to end up with a central, random shaped "window" that will show part of an image underneath

The Help/About Shapes indicates that this can be done, but doesn't say how.

 

[Bill Dilworth]

Create as many shapes as are required to leave the window, then select them
all at once and 'group' them (right click | grouping ... | group).

After this, they will be able to be treated as a single unit.

Bill Dilworth, MS PPT MVP

How do you combine two shapes, drawn using the freehand tool, and then

combine them to create a fill area.

The effect I'm after is to end up with a central, random shaped "window"

that will show part of an image underneath.

The Help/About Shapes indicates that this can be done, but doesn't say

how.