Clean Install Win98

Anne Ugazio

TS Rookie
I am to attempting to clean the HD of an old laptop prior to donating it.
I have the Win98 cd that came with the computer when it was new.
I have accessed the BIOS, changed it to boot from the cd
When I type
D:\win98>FORMAT C: enter
I get
Invalid Drive Specification
rather than the directions to proceed with the formatting. What haven't I got right?