¥ If the disk has been used with an Apple IIGS—or with a computer that uses the same disk format as the Apple IIGS—an icon representing the disk will appear on the desktop.
Click the new disk's icon to select it, and then choose Initialize from the Disk menu. You'll see this dialog box.

Go on to step 4.
 

4. Type the name Practice.

There are some restrictions on the names you can use for disks. You'll find complete information on naming rules in Chapter 3 of the Apple IIGS Owner's Reference

Section 4: Experimenting with the Finder

57