You can call Apple Customer Support 1-800-767-2775, provide the Serial Number and specifications of the Mac, and for a small fee, a replacement set of system discs (if available), can be ordered.
However, the discs will be for the original version of OS, that was pre-installed, when the Mac was manufactured.
Often you can get an Istall to work without Disc #2.
That second Disc thing happens frequently, the best way around it is to do a Custom install, and eliminate enough Printer Drivers, Languages, Fonts, and Applications you don't need... then it may skip #2 altogether.
But first try Disk Utility.
1. Insert the Mac OS X Install disc, then restart the computer while holding the C key.
2. When your computer finishes starting up from the disc, choose Disk Utility from the Installer menu at the top of the screen. (In Mac OS X 10.4 or later, you must select your language first.)
Important: Do not click Continue in the first screen of the Installer. If you do, you must restart from the disc again to access Disk Utility.
3. Click the First Aid tab.
4. Select your Mac OS X volume.
5. Click Repair. Disk Utility checks and repairs the disk."
Then try a Safe Boot, (holding Shift key down at bootup), run Disk Utility in Applications>Utilities, then highlight your drive, click on Repair Permissions, reboot when it completes.
(Safe boot may stay on the gray radian for a long time, let it go, it's trying to repair the Hard Drive.)