To add a IDE drive, you must mount the drive in the right position and remove the IDE bracket on the face of the case. An IDE bracket is just a simple piece of plastic on the front of your case. When removed, your drive can then be accessible from your case's front. Remove one such plastic bracket by only pulling at it and it will come loose, then mount your drive in the case with the door facing frontwards.

Currently, your drive will not stay in that position unless you mount it with some scrues, so do so to both sides of the drive. Then, connect an IDE ribbon cable to one side of the ROM. The other side of the cable should run to the secondary IDE slot on your motherboard. The primary is the one that runs to your master hard drive, and the secondary runs to your rom drives. You can connect up to two rom drives on one cable, as it will have one end that connects to your board, one end that connects to a drive, and a middle connector for another drive. Run a power cable to the drive as well.

As for connecting a sound cable - it can be done, but it actually is not necessary. Should you want to listen to music from your cd player, you're better off just copying the music to your hard drive, then listening to it. This will cut down on your used system resources, and for slower computer skipping will be eliminate.