Do I have to mount this device or what?
The usb storage is accessed like a scsi hard drive. So if you have no scsi system this would be most likely /dev/sda1.
Try to mount the device manually (as root).
If this doesn't work make sure that you used the appropriate device file and that the modules usb-storage and sd_mod are loaded.
If it works add a line like
/dev/sda1 /mnt/usb auto noauto,user 0 0
You should then be able to mount the reader as any other device.