Almost all new disto comes with USB enabled these days
Here is command to do so
1) Create mount point
mkdir –p /mnt/usbhd
2) Get list of partitions
fdisk –l
3) Your usb device assigned as mass USB storage and assicable as SCSI device
4) So if you got only one partition and no other SCSI hardware here is mount command
mount /dev/sda1 /mnt/usbhd
You must login as root user to run above commands