Can't figure out how to "cut out" a section of my drawing

Hey everyone. well I'm sure this is probably gonna sound basic to all you veterans out there with alot of experience, but I guess I dont know what I'm doing at all, so I'm having a problem here.
I'm trying to use photoshop to make the number Zero, but I dont want to just type it in, I want to design the way the zero looks myself to customize it for a logo. I started off by using the elipse tool, and drew an elipse, and filled it in, making an egg-like shape. I was going to make it look like a zero, by using the marquis elipse tool to select the part of the inside I wanted to cut out, and just cut it out. But, everytime I draw the area I want to cut out, whenever I let the mouse go it just makes that selection. After that, I can't adjust it at all, it just cuts out the original elipse that I drew. It makes itdifficult to make the proportions exact, I dont want the zero to look lopsided on one side or another at all. I tried to adjust the selection using the edit>transform>scale option, but for some reason, when i use the move tool, or delete tool to remove the selection, it still just cuts out the original selection I drew before scaling it. Thanks for any tips you might have.

Explore the pen tool and shape tool.

You can try using the Ellipse Tool; put the setting on path (the icon in the upper left corner, between/below the image and layer menus if you're using PS 7). Then just draw the two shapes and adjust as needed. When you're ready to go, go to the paths pallete and ctrl+click the path you made; it should automatically subtract the inner path to give you your zero. Then just fill it with whatever color you like.