Second HD on RHEL 6

[Nicosia Gaetano]

Hi,

I have installed RHEL 6 on a server that has 2 Hard-Disk. The redhat 
setup has installed the software on sda.
1) How can use sdb ?
2) In disk management I found these options for Unit format:
     - Master Boot Record
     - GUID partition table
     - No partition
    Wich option I must to use in order to format the disk ?

Thank You and Best Regards

Gaetano