Before you can ride your snowmobile, you will need to pay a $35 annual fee to receive a decal, valid from December through April 1. This will entitle you to ride on designated areas, such as those in the State ORV program. This program features a variety of trails and roads in state parks, state trust lands, habitat management areas, and forest service areas. You can find more information about the State ORV program on their website.
Check out these Robertson, WY ATV/OHV resources: