Please, read the title. What i have to do to fix this? please help me! i need to transfer some important data to the primary hdd. thanks!

The first thing to do is to check if the computer bios detects the hard drive. It could be something as simple as the wrong jumper set. Since the name is hdd, that tells me that it is an ide drive. If it were a scsi drive, you may need to load the kernel module for the controller.

If you only want to transfer data to the main drive, and you don't have a hardware (ie not set on slave or cable-select) problem, then you could try booting up a live distro like Knoppix. If the drive is detected in knoppix then you can mount the drives and transfer the data.

I have assumed up to this point that your hdd drive is a hard drive, and not an ide cdrom drive. With a 2.4 version kernel, a CDROM drive might be mounted as a SCSI drive instead. You should supply more information with your post.

Does the drive show up if you use the command: fdisk -l
You might need to su to root before using the command.