There is a lot of online info and videos with more details, but I want to address some common mistakes that an occasional user may make. If you hit a nail, rock, or whatever that skins the chrome off the cutting teeth, you must file the worse damaged tooth first and back to where no damage shows. The angle must be kept close to what is marked on the file guide. All other teeth, even if not damaged as much, must be filed back to the same size. If badly damaged a new chain might be easier. If a gas saw, it is easier to do a touch up every gas tank fill. If no damage, 3 strikes per tooth doesn't take long but keeps your saw performing as it should. If a battery, I recommend touch up sharpening every 2 charges. If nothing is ever hit, touch up sharpening will be all that is ever necessary. When you chain gets dull, it gets hot and starts to get loose. If you continue cutting, this can cause bar wear and be a hazard. Be sure your chain is getting oiled. I won't address taking off the bar cover and cleaning, etc., because so many different styles of mounting. I love my little Stihl because it has a rotary tightener instead of bolts and nuts and a thumb wheel tension adjustment. I would refer to your manual on how to loosen bar just a bit then tighten chain so bottom on guides or at top of the bar when pulled up tightly. See photo. Most saws have a flat blade screw adjust for this, some a hex head bolt. Once adjusted,.then tighten the bar cover with proper wrench or hex key. When you stop to sharpen, check the chain tension by pulling up. It should be a bit looser because it is warm, but not way loose or super tight. Note sharpening angle marked on the guide and other hand fingers holding that angle. Remember to keep guide flat and not rock up and down. I have a bar holder clamp I made, but to keep things simple a 2X4 block works just fine for holding bar from moving around. Note photo of how to safely move chain forward. Lift off 2X4 block slightly and put one hand on top of bar on the last sharpened tooth and other hand on the bottom a bit up from the saw and rotate forward to you favorite sharpening position. I always wear gloves and love my Stihl stretch gloves because they are light, but very tough and come in women sizes.