In this tutorial we create a hatch as you sometimes find them on aircraft.
Start with placing guides to make drawing the objects easier.
You can add a guide from the menu Window - New Guide
We start with a white circle. The guides help to make it perfect round.
There are two ways to create a circle. You can use the Elliptical marguee tool to
make a selection 
and fill it, or you can use the Ellipse shape and fill that.
Linear Mode
