RV Repair: battery wiring for Bigfoot camper, deep cycle batteries, black and white in colour

Question
Hi Eddie,
I would like to know how to wire two 12 volt deep cycle batteries together to boost the battery power and lengthen the charge.  Secondly, I would like to know where to connect the three wires coming from the camper to the battery compartment.  They are red, black, and white in colour.

Thank-you very much.
Rod Munch

Answer
hook pos to pos and and - to -  as far as the wires red to + black TO + and white to _ the black one is the only one one I have doubts on put it on last  this sounds bad but when you put it on th + side if it starts sparking and trying to get hot  it may be a ground hard to tell with out looking at it

let me know if need more info