/dev/hda4 represents the 'extended' container partition to hold the
extended logical partitions like hda5.

I think /dev/shm is a new thing in 2.4.x.  I am guessing it is for
'Shared Memory'.  

A second HardDisk will show up as device hdb.

To partition use fdisk.

To format use mkfs.

Here is a detailed link:
http://www.redhat.com/docs/manuals/linux/RHL-7.3-Manual/ref-guide/s1-filesystem-ext3-create.html


Good Luck