You will need a drive pre-loaded with the TetherX software which will also have the TetherX serial sticker.
To open the TetherBox unscrew the screws on the cover and lift the cover
Install SSD
Slide the new 2.5" drive into the drive bay, ensuring the DATA connections are fully seated into the connectors of the SATA daughter card (A).
Secure the drive to the bay using the two small silver screws that were included in the box (B).
Set the drive cage bracket inside the TetherBox (C).
Close the TetherBox