Raid help-dead drive

Running W2k Advanced Server – 4 hard drives in a Raid array – have a hard yellow light on front display panel indicating drive 1 – how do I find what level RAID is configured? – I did run a consistency test from the RAID utility which I accessed during boot up and it said that one of the drives was dead. What do I need to do now?
Do I need an exact match to replace the drive?
I’m assuming because of the light that it is drive 1 that has failed. Unfortunatly, I am coming into this blind because my predecessor was fired and no documentation could be found.
The server is a Micron NetFrame 5200 it has a Mlyex array controller.
If someone could help or at least give me an idea of where the best place would be to seek help