It is unclear to me why your CD-ROM is named R:. Here are some
instructions for how to set up DOS to access a CD-ROM drive. Go
through them and verify that you have set up your CD-ROm correctly.
These instructions make the CD-ROM drive D:.

Here is how to add your CD-ROM driver to the boot disk. The boot disk
might be drive C: or it might be a Windows Startup Disk that you can
insert into drive A:.

The CD-ROM driver will normally have a name with the letters CD in it
and it will have the extension .SYS. One way to get a CD-ROM driver is
to run the installation program that came with the CD-ROM. Also, you
can usually get a driver from the web site of the companmy that made
the CD-ROM. Or you can search your C: drive for *CD*.SYS.

Using Notepad or any word processor, make a text file, name it
CONFIG.SYS and add it to the boot disk.  This file should look like
this, but with the name of your CD-ROM driver in place of
CDDRIVER.SYS:
DEVICE=CDDRIVER.SYS /D:MSCD000
DEVICE=HIMEM.SYS

Add a copy of MSCDEX.EXE to the boot disk. You can get MSCDEX from the
folder C:\Windows/Command.

Using Notepad or any word processor, make a text file, name it
AUTOEXEC.BAT and add it to the bootdisk.  It should look like this:
MSCDEX.EXE /D:MSCD000

Bill Starbuck (MVP)