After attaching ur usb drive to the port , Give this command :
#mount /dev/sda1 /mnt
After that if u want to see ur usb contents
go to /mnt with command
#cd /mnt
check its contents by giving command
#ls
After finishing ur work, unmount the usb by giving this command
#umount /mnt
or
#umount /dev/sda1
Enjoy:
Gaurav