A mount point is a directory that is used to attach the filesystem to the file tree. If you noticed unlike windows there are not seperate "drives" for the CDROM, floppy drive. (No c: or d
. Everything is under /.
You need to create a directory using the mkdir command. In a console window.
mkdir /mnt/usb ( or whatever you want)
Add an entry in the /etc/fstab file, assuming it is formatted as a FAT32.
/dev/sda1 /mnt/sda1 vfat umask=000,users 0 0
This also assumes this is the only USB, Firewire or SCSI storage device on you system.