Danby dpac120068 Air Condtioner, where does the hose go? and do you fill the tank in the back with water?

The hose goes into the empty tank or tray inside (if it's the drain hose like a garden hose). When the hot side of the system goes past there it evaporates the condensation dripping into it. If your talking about the big 4 inch hose, that goes out a window to get rid of the heat from the room.

Hose goes into a bucket or out a window, drained, etc. it's the drain hose for the condensation. alternatively you can use the tank to catch the condensation, which must be emptied periodically.