You can put your another harddrive to use like this (in this example first HD is /dev/sda, second /dev/hda). You'll have to do all of this as root.
1) Optional: Install "cfdisk" and/or "qtparted" (last one works in XWindows only)
2) Run "cfdisk /dev/hda", "fdisk /dev/hda" or run "qtparted" and choose "hda"
3) Erase all existing partitions
4) Create a new partition(s), make sure it's partition type is "Linux", pay attention to the partition number(s)
5) Commit changes (write partition table to disk)
6) Run mkfs.ext3 /dev/hda1 (or several times, once for each partition number)
7) Add a mountpoint for your new partition, for example "mkdir /newpartition"
8) Add an entry to /etc/fstab. Basically simple copy-pasting, but check "man 5 fstab" to be sure
9) Try mounting the partition with "mount /newpartition" or "mount /dev/hda1"
If that does not work then nothing will