USB booting :: Problem Accessing USB Device

i would like to know how to access/mount a USB Camera/Mass Storage in DSL. i know the answer is probable pretty simple. thanks, please help out.

mount /dev/sda1

tried. all i get is 'invalid block device'

i've already tried different configurations of that command
and devices by looking in /dev but have had no success. i've also tried to use hotplug.

plug in the stick and try dmesg to see the devicenode of the usb-stick

original here.