to mount it if you need to know the device name and it needs to have a filesystem.
You should be able to see the device the list option with fdisk. Ie, as root
If this is a "new" disk you'll have to decide how you want to partition it and what filesystem you want to put on it.
You can make partitions with fdisk or cfdisk (or many others), and you can format the parition(s) with commands like mkfs.ext3, mkfs.ext2 etc.
Once you have done that you can mount it with the mount command, and you can also setup your system to automatically mount it by putting an entry in your /etc/fstab. For example if your new disk is sdc and you and it contains one ext3 partition, you could automatically mount it at /data with the following line in your /etc/fstab
/dev/sdc1 /data ext3 defaults 0 2
If you have not done so already googling for something like "linux new disk howto" should provide useful information.