Switched 2 days ago!!! Already need help!

Just pulled my new iMac 24 out of the box on Friday. So far, I THINK I'm gonna like it------just not totally certain, yet. I have several questions but will only ask one for now. I know my OS is 10. But there must be additional numbers to follow the 10. I am trying to install my older and very comfortable Logitech Mouse, but the install CD shows Mac OS 8.6 to 9.2, so I went to Logitech website hoping to find a newer model. Bingo! The newer model works on Mac OS 8.6 to 10.3.5. I know my OS is 10. But there must be additional numbers to follow the 10. I have been looking EVERYWHERE!!!!Where do I find these numbers?

Top-left, under the blue apple — About This Mac.

Go up to the apple in the left hand corner & click on the about this Mac & it will give you all the info you need

your mac is running 10.4.x

You probably don't need drivers. Plug it in and see what happens. I use the Logitech driver only because I want the scroll wheel to mimic pressing the Option key and double-click when I press it.