Select the "Add" button to begin.
The first thing that can be entered is the new partition's name. "hdb1" already appears in the list so that make things easy.
Then the filesystem type needs to be entered, this one uses "ext2".
The "Mount point" is where the new file system will appear in the directory structure. O'Reilly's "Essential System Administration" describes it well:
"Mounting is the process that makes a disk's contents available to a system, merging it into the system directory tree. A filesystem can be mounted or unmounted: that is, it can be connected or disconnected from the overall UNIX filesystem."