Yep. That is a very good place to start. What size battery do you have -- group 24 or 27 or 31?
In any event, get a new one -- who knows how the old owner maintained it? And get a Battery Minder or something similar, to keep it charged up at all times. That will hugely extend the life of your battery. Letting it die will cause it to really, really die. Don't ask how I know this. Very expensive lesson for me.
Once you put the new battery in (make sure the battery kill switch is in the ON position), let us know how it is going.
Hang in there. Yes, there is a steep learning curve for trailering, but it is incredibly worth-while. We were all newbies once. I hope you can learn from our mistakes!!