You need to focus on the IDE side of things. Your motherboard has one 40 pin IDE connector. This means you can connect up to 2 IDE devices to that channel. If the cable to your CD-ROM drive has 2 connectors you can connect the IDE hard drive to the spare one, or it may be more practical to switch them around. Without knowing the location of the drive bays in your computer it is difficult to say which would be best.
Perhaps the simplest thing to do would be to remove the connector to the CD-ROM drive and temporarily connect it to the IDE hard drive.
In this case you need to know how the CD-ROM drive is jumpered. You should Google for the HDD and CD-ROM drive manuals and/or look at the jumpers and the informative stickers on the drives, and make sure the HDD is jumpered correctly. Also connect the Molex power plug. Do all this with the PC powered down and disconnected from AC, observing proper static precautions.
