Yeah just go with the file and guide unless youa re comfortable freehanding. The handheld grinding type tools may work, but there is the extreme temptation to take off too much metal, and its also easy to burn the chain as fast as those buggers rev up. A real grinder is worth the money, but probably only if you are in the business and go through a lot of chain/don't have time to file. Most people can file chipper, semi chisel and round full chisel pretty well with some practice, even freehanding. You ahve to remember that the depth gauges need maintenance too, to keep your proper angles and not to take off too much metal at a time. Unless the tooth is actually damaged, you only want to take maybe 2-4 strokes with that round file. I touch my chain up after every couple of tanks of gas and go verthe depth gauges after 3-4 sharpenings. It works. I started cutting as a kid adn it took me awhile to figure out how to keep my chains maintained, but these links the guys gave you plus the search function will help a lot. My best advice is to keep the chain sharp, keep it properly tensioned,a nd out of the dirt.
