iMac G3 question mark floppy disk

Hi there.

Recently I have got a iMac g3 working again but it has no operating system installed on the hard drive. The issue is that I have not been able to install Mac OS on them. The only disk I have been able to boot is Mac OS 9.1 but the open firmware version is too old. I have made a 8.6 disk with different computer and that sort of works. When I put the disk in the system and then hold c on boot it will find the disk and it looks like it is starting to boot but then it just shows a floppy disk with a question mark in it.

Thanks in advance.