If you are using a real optical drive and a physical CD you can skip this step.
A virtual optical drive is needed to read the CD image file that you have uploaded to your IBM i system in the first step. By convention, these are typically named OPTVRTxx, where xx is a number from 01 to 99. You can see the all the optical drives defined for your system using the WRKDEVD command.
If you have a virtual optical drive already defined you may be able to just use it if it is not already attached to an image catalog. To determine this use the WRKOPTVOL command.
This will list the optical volumes currently in use as well as the drives to which they are attached.
If you have a virtual optical drive you can use, make sure it is varied on and proceed to the next step.
If you've determined that there are no virtual optical drives available for your use you can create one using the CRTDEVOPT command. For example:
CRTDEVOPT DEVD(OPTVRT01) RSRCNAME(*VRT)
Now you need to vary on the drive as you would normally do. This makes it available to the operating system. For example:
VRYCFG CFGOBJ(OPTVRT01) CFGTYPE(*DEV) STATUS(*ON)
Remember this drive name for the next step.