You have a major dinosaur, of 1993 vintage.

The 180c came with OS 7.1, and the latest it can use
is of the 7.6.1 persuasion. Don't even think OSX.

To hook up a CD-ROM drive, you'd need to find one that
uses SCSI (Small Computer System Interface). The 180c is
way before USB or firewire. And you'd need to get an adapter
to connect the SCSI cable to the HDMI port (little square
thing) on the back of the PB. These days you're likely to
get a drive with a SCSI-2 plug. You'd then need to get an
adapter to go from the SCSI-2 plug (small) to the SCSI-1
port (large) on the HDMI adapter.

I went through this exercise when Leslye unearthed a
shoebox-full of 3.5" magneto-optical discs containing
treasures she couldn't bear to lose. Fortunately we have
a PowerBook G3 running OS9, so a device driver wasn't an
issue. In the case of OS7, you'd need a driver for that
CD-ROM device: LaCie's SilverLining is my choice.

Then you get to find software for OS7.

I don't recommend this for a newbie, but if you're
feeling adventurous, give it a try.

Hope this helps.

What software is on the PB now? What is the system version?

What is the name and version number and OS requirements of
the genealogy software. You probably can't put the CD-ROM onto floppy.

Try Low-End Mac for good information on oldies but goodies:

http://lowendmac.com/macos.shtml

I'm often wrong, but I don't believe you can get 7.6.1 except as
an update to 7.6, which doesn't seem available.