Driving a snowmobile down a hard-packed trail can be like riding a motorcycle, but without the need to balance. You use a thumb lever throttle instead of a twist grip to control your speed and there's no clutch lever or need to shift because a snowmobile operates with a continuously variable transmission (CVT).
You sit or stand on the machine and press the thumb lever on the right side of the handle bar to move forward and pull the left-hand brake lever to slow down or stop. Steering is through the handlebars where you naturally move them in a in a turning motion either left or right, and it's suggested the rider move their weight or lean the direction they want to go for better stability.
Off-trail riding in unpacked, typically deeper snow requires more physical effort and steering is done as much by moving body weight around as it by using the handlebars. Often in very deep snow turning is accomplished by using a combination of throttle, rider weight and turning the handlebars in the opposite direction (often referred to as counter steering) to initiate a turn.