Here is an example of a simple IDE cable that can have only one device on it. One end plugs into the motherboard, the other into your device (hard drive or CD/DVD drive)
http://www.shuttersto...white-background.html
And here is an examp[le of an IDE cable that can have two devices on it (note the extra connector in the middle).
One end goes in the motherboard (blue end), the master device goes at the end of the cable (black), the slave device connects to the midle of the cable (grey).
http://www.tacticalpa...omputer/ide_cable.png
You need to see what IDE cables your computer has and you may need to change your existijng simple IDE cable to one that can take two devices.