That's very vague vernong.
Here are the basic steps:
1. Make the RAID driver diskette, by putting the RAID drivers on a floppy disk.
2. Install the hard drives needed for the RAID level you are going to do.
3. Go into the RAID setup menu via BIOS.
4. Set the RAID level you want.
5. Set CD as first boot priority, save settings, and reboot.
6. Insert the Windows CD.
7. At the blue screen, look at the bottom for a message, saying to install any third party RAID drivers. Press F6.
8. Follow instructions on installing the RAID drivers.
9. Then just continue on, installing Windows as usual.
It may vary between different motherboards, but those are the very basic steps on how to setup RAID.