In linux, harddrives aren't listed as C/E/D/G:. They are listed like so:

/dev/hda1

Explained:

/dev
::This is the device directory

hd
::This means that the device is a harddrive(HD)

hda
::This means hd A.

hda1
::This means partition one on hd A.

So to format what used to be your C:, you would type:

fdisk /dev/hda


[Note: I am kinda new myself; you can confirm what I said at linuxdocs.org.