Imac G3 Screen Shifted

Hello
I have just installed openSUSE 10.2 and I am very pleased with it. However, whenever I start the computer, the screen is shifted to the left and I cannot get it to be centered in the middle of the screen so I can see everything. How do I fix this problem? And if you can, make it kinda simple, I am completely new to any sort of Linux distribution. I am aware that there have been posts like this before, but either they did not make sense to me or I just couldn't understand what they were instructing me to do.
Thank you so much!

~Joe~