Disconnect the positive battery cable from the battery. Remove the left side engine cover (as sitting on the machine) by removing the 8mm bolts from its perimeter. Depending on which model atv you have, it may be easier to remove the footwell to increase access. Once removed, you will be able to view the starter gear. Remove the snap ring in the center of the gear so it may be removed from the starter.
From the right side of the machine, locate the 8mm hex bolts at the base of the starter (no need to remove the phillips head screws). Remove the only wire lead connected to the starter and it's out.
Simply reverse these directions for the installation. Don't forget to hook up the ground wires if they were attached by any of the cover bolts.