Flaps,
You should have got Graphic Converter bundled with your iBook. You can do a fair amount of editing with it. The latest version is 5.7.3 and you can download it
here. It's a lot cheaper than Photoshop and has a lot of the same features.
Trip: Yes, I know. Mrs AM has taken the car to London, so I'm stuck in The Shire. That's my excuse anyway...