You can fix the background to the tank using either silicone or if you think you would want to remove it at anytime, you could use velcro. You will need to stick the velcro to the background and the tank using silicone or super glue.
Watch the vidio below to see how to set up a vivarium using our BF3D background
BF3DER EXTRA RELEIF BACKGROUNDS.
IDEAL FOR LARGER TANKS.