Matt; First turn off your battery disconnect. If you have two 12 volt batteries then put them in side by side with terminals matching, by this I mean positives at one end ans neg. at the other. Using your short jumper cables connect the red to positive terminals and black to neg. Connect the red cables from the coach to the positive of one of the batteries (doesn't matter which one as long as they reach and are not stretched tight). Now connect the black wire from the coach (ground) to the other battery ground. When done you will have the red coach cables to one of the positive terminals and the black ground to the other batteries negative. Always connect the ground wire last so you don't short out any wrenches. Use a multimeter to verify you have 12 volts at your battery disconnect, not 24 volts before turning it back on.
Google "12 volt side of life" for diagrams if you have any doubt about how to do this.
Blessings; KDK