If you have both a SATA drive and an IDE drive, the data port each must be connected to its proper controller port using the right cables. You also will need the proper power supply connectors from your PSU to plug into the drives (4-pin Molex for IDE, SATA power for SATA).
On many motherboards today, there are one (sometimes 2) IDE ports plus 4 (or more) SATA ports. Some very recent mobos have begun to simply NOT include any IDE ports. If that is your situation, there are two options. One is to buy and install an IDE controller card in a PCIe slot, and connect your IDE drive(s) to that. The other is to buy an adapter that plugs into the data port on the back of the IDE drive and provides a SATA port to connect to one of your mobo's SATA ports. Just make sure the adapter you buy allows an IDE drive to plug into a SATA port. You do NOT want the reverse type of adapter that allows you to plug a SATA drive into an IDE port.
Either an IDE controller card or an adapter can work, although some people have had trouble with some of those adapters.