IDE Cables are pretty nifty, able to host two devices on one cable. There are some tricks, though.
First, there is a Right Side and a Wrong Side. In the picture, there are notes about Pin 1, and while this pix isn't clear, IDE drivers have a "stripe" or a colored or marked 'edge' to them - in this pix, it's a red stripe. But it can be dashed, hashed, white - any color. But it is distinct from the 'other' side. That striped side is considered "Pin 1".
Second, the devices will have 3 different settings - Master, Slave or Cable-Select - using little jumpers on the back of the device. Most, by default, are set as Master or Cable-Select.
Third, the Final Connector on the IDE cable is the Master Connector. The Inner Connector is considered the Slave Connector.
Since you're only dealing with one device, plug the Last IDE connector into the optical drive, and the other end to the motherboard. (And no, it doesn't matter which "end" - these are two-way comm cables so signals travel back and forth constantly.)