Good help books for my Canon G12
There is a lot of free generic information online. That is all you really need to get started. Just learn the relationship between fstop, shutter speed and iso and how they vary together to give an exposure. Learn when to use a large or small fstop, speed and iso and you will have the basics for any camera. Not just the G12.
As far as composition, color, etc., lots of information can be borrowed from the art world eg what makes a good picture. It's been so long that I don't have specific sites in mind but a quick google should do the trick.