A chain saw is such a potentially dangerous tool that anyone who doesn't know how to maintain one very likely doesn't know enough to operate one. Do your homework, there are likely some good professional videos on line from which you can learn how to operate a saw, as well as maintain it. Read the manual. Use safety equipment, including chaps. Maybe start by going online and finding some images of wounds and other injuries from chain saws. Then find some of the many, many videos of dumbasses falling trees on trucks, cars, and houses.