iMac OS 9.2 install issue...

I am new to the MAC systems.
I came accross an imac that needed a new hard drive because
the one that was in there was bad.
I installed a new drive and the system doesn't find the drive.
The drive works fine it my intel system.
If I try to install Mac OS 9.2 the systems says it needs a firmware update.
When I do it can not find the hard drive, so it tries to load it on the cd drive,
which fails of course.
I'm not sure what to do on these Mac systems.
Is there something I am missing that is specific to Macintosh?
Can someone send me some mac support sites?

Thanks to anyone that responds.