Welcome all!
Mehim, what is your budget?
Newbie, I'd go get a battery tender from harbor freight or some place like that. It's not really meant to be a battery charger but it will slowly charge the battery. That will tell you if it's a parasitic draw or a different problem.
I joined the Wisconsin ATV Club for those very same reasons. They have a very good set(s) of maps of almost all trails in Wisconsin.
https://www.watva.org
They have a load of functions, trail rides, get-togethers, etc. Trail riding info, maps, news, etc.
Good luck, hope this helps.
Dave
Marinette, Marinette County