I suppose you want to install the OS now...?
As well as that error message, was there an error code of some kind?
Open up the case, and verify that you've plugged in all IDE / SATA cables correctly, and that you've set the jumpers (Master / Slave / Cable Select) on CD-ROM drive(s) and hard drive(s) to correct configuation. Also verify that all molex power cables are plugged into the drives.
Power up the PC, go into your BIOS, and make sure that you've set the CD-ROM drive as the primary boot device in the device boot order.
|Desktop PC| |Macbook Air 13" (Mid 2013)|
|Windows 8.1 Pro (x64)| |AMD FX 4100 Black Edition 3.6 GHz @ 4.0 GHz OC| |Arctic Cooling Freezer 13 PRO| |Gigabyte Nvidia GeForce GTX 560 Super Overclock 1GB| |ASUS M5A78L-M/USB3 Motherboard| |Samsung 840 Pro 256GB SSD SATA III HDD| |Kingston HyperX 8GB PC3-14900 DDR3-1866| |OCZ ModXStream Pro 700W Modular PSU| |NZXT Vulcan Micro ATX Case|