2 Six-Volt Battery Hook Up

[LilaLS]

I have a 2015 Trailmanor and I am not certain about hooking up my 2 new 6 volt batteries. I accidently misplaced my original picture of my battery hook up.
I have two batteries on the tongue. I have a red jumper cable that I assume goes from positive to positive leads on each battery and the other cables go to the negative terminals. Can someone verify or does anyone have a picture. One time I did it incorrectly and I reversed the polarity of one of the batteries!
Thanks for any help.