As a rule you always mount a device on the filing system tree of Linux.
You can ask Linux to tell you what is the name of the partition of the USB device by command
From the display you can see the capacity of the hard disk to tell it is the USB device. Also USB memory devices are factory-partition with type Fat16 or Fat32 filing systems.
Say the device you want to mount in the USB is sdb1 you can mount it with commands
mount /dev/sdb1 /mnt/sdb1
If there is output from the last command then the device has been mounted successfully.
When you finish make sure you unmount the device by either
Premature withdrawal of the USB device without properly unmounting it can cause damage to the files. Yes remember to unmount use the command "umount".
As a rule only the root user has the privilege to mount devices.