How does G02 & G03 work?

Hi,

I need help understanding the G02 and G03 commands. I don't understand
the I, J K thing and the rest of the things about it. The references I
have on those commands devote about a paragraph and don't give me a
complete picture of how to use them.

Can someone point me to a reference on the web that gives enough
information to actually explains this? Or something else????

Thanks,

Clint Bach