The second hard disk is only used for an installation with RAID. If you have ordered an installation without RAID, the second hard disk is not used. If you want to use it, you have to partition, format and integrate the hard disk into your system.

Following a manual for Linux:

Partitioning the hard disk

fdisk /dev/sdb

within the command interface press the following keys:
create a new partition Key n
Partition number Key 1
Accept default of start cylinder Return
Accept default of the end cylinder Return
Write partitoning Key w

after successful partitioning the hard disk must be formatted

mkfs.ext4 /dev/sdb1

Now only the mount point of the hard disk (the directory where it should be accessible) has to be added to /etc/fstab. Please note that the directory must exist before. The entry could look like this:

/dev/sdb1 /second hard disk ext4 acl,user_xattr 1 2

Under Windows, you can partition and format using the dot:
Start => Administrative Tools => Computer Management => Disk Managment.
There you can select the Unallocated storage with a right click and create a simple volume.