The pattern feature is a powerful thing to use.
It is created with the Triball.
-To make a rectangular pattern first select what you want to "patternize". A hole or something.
-Triball on.
-Rightmouse a outer red Triball handle, and then rightmouse the second Triball handle.
The reason that two handles have to be selected is that a 2D orientation have to be done.
After the creation o the pattern, it will show in the scenbrowser and in the scene. You can drag and drop Assys, Parts and Intellishapes in and out of the pattern structure, in the browser. Just make sure you drop on the right ikons in the browser.
-If you dont see any pattern (the patternfeature itself) in the scene, rightmouse the scene/ Show, select Show pattern.