Just double click on the My Computer Icon, and then Double Click on the Optical/CD/DVD Drive Icon you see there.
It will most probably start the Autorun file.
If that doesn't happen, you can always Explore the Optical Disc by Right Clicking on the Optical/CD/DVD Drive Icon and clicking explore.
You will see the contents of the Disc, you can then either start the process by double clicking on the autorun Icon or the setup or install icon.
Depending on what you see there in the contents of the drive.