I was doing a job with a bunch on Dells the other week:
I would imagine the blue wires you are talking about are SATA cables and connectors?
Connect the drive, go into your bios (might be F2? It should tell you somewhere on the logo screen immediately after power on what key it is)...you have to enable the second SATA port - it might be under interfaces or drives (can't remember now).
Hope this helps