Enter CD-ROM 1 in the CD-ROM drive.
When you see the following screen, hit "install":
Enter your product key (it can be found on the inside of your jewel case)
If the CD key is correct, you should see this screen, otherwise, you're a naughty boy.
Click "Next"
Click "Yes"
Click "Next"
Click "Next"
Click "Next" and make sure "Install Punkbuster" is enabled.
Click "Next"
Click "Install"
Insert CD-ROM 2 in the CD-ROM Drive
Insert CD-ROM 1 in the CD-ROM Drive
Click "OK"
If you want shortcuts on your desktop press "Yes", otherwise press "No"
Click "Finish"