I wasn't familiar with that vehicle...had to do a search. I see it's a side by side with a CVT and low, high, neutral and reverse gears.
I would start with following the shift linkage from the shifter to the transmission. Look to see if it has any adjustment. It might be as simple as loosening a nut, adjusting linkage and retightening.
If this doesn't work I'd suggest finding (or buying) a service manual. I see a manual available online for purchase.
Sorry, this is the best I've got!