If you run those wires straight to your battery you will have a very flat battery in about 3 hours!
You need to run one of the the wires to a switch mounted somewhere on the dash and a live feed from the fusebox to the switch, the other wire from the fridge needs to be earthed and heres the bit I cant help with without knowing the exact colours of the wires because one is a live and one is an earth.
It would pay to use a lighted switch so you dont forget to switch it off when the engine is not running, 12 volt should only be used when the van engine is running and not when sited.