As it may happen sometimes you either work inside a terminal client or you find yourself using a Linux system or a filemanager which does not automatically mount volumes (meaning, for example, usb sticks or external hard drives). The next solution will help you on your mounting efforts.
Mounting devices
First you need to find out what is the address of the device you are trying to mount. Attach your device to your computer and run, for example, gparted to see the device’s address (should be something like /dev/sdb1).