What operating system are you using?
You say the PC knows its there, it just won't connect. What do you mean. Do you mean that you can see the DVD drive in my computer but can't write to the drive?
On the installing the CR ROM as a slave. On the cable you connected to the DVD writer, there should have been another connector, you can connect this to the CD-ROM, and connect one of the spare power connectors and that is pretty much it once you have located the drive in a spare drive bay.