trolling motor help

[maxwell.riddle]

I recently got a bass boat. it has a trolling motor on it but isnt hooked up. i kinda need some help. so where you plug in the trolling motor i have a switch that reads 2/12v (charge) on top, 12v in the middle and 12/24v (run) on the bottom. i took the face plate off to look at the wires and they come out of both the switch and the receptacle for the trolling motor and go into 2 plastic conjunctions(im not good at electrical vocabulary. excuse my ignorance). but on the one end i have a hot and ground wire coming out. so i have 2 hot(power) and 2 ground wires back by the batteries.

i bought 2 new batteries but i dont know how to hook them up correctly. also i do not see a charger anywhere and i dont know how exactly the switch works or the difference between 2/12v, 12v, and 12/24v. if anybody can help me that would be great. thanks!

here is a pic of the faceplate with the switch and receptacle if it helps