Very newbie to YDL!

[N0DIH]

I tried to install YDL 3.0 on my 8500/G4-450/44GB/18GB/512M ram.  The 2 SCSI
drives are on a 2940 SCSI card flashed to Mac, and it would not see the 18GB
at all, and all it wanted to do was format the 44GB drive, which is a good
active HFS partition that I cannot erase at this time.  I had a 500 MB drive
on the external SCSI but it didn't like the size.

Do I need to add a large clean drive for YDL so it can have it's way?  I am
fearful of losing Mac stuff that I have on the HFS.

Does anyone have advice?

Where is best install instructions to get started and to know basic command
structure on YDL?

Thanks!
Thomas Martin