Sharpening your saw, with all the chain sizes out there you need the right round file or some call them rat-tail files. You only cut in one direction, pushing away from your body. The usual stroke count suggested is 3, I believe it depends how much pressure the person doing the work applies since that will dictate the amount of material cut. We will just stick with 3 strokes for this.
First off, have gloves, look at the teeth and see how much work is needed before you start. Select your file, larger size saws use larger designed tooth and chain layout, smaller saws use smaller designed tooth and chain layout.
Here is the file holder I have, which is STIHL, which is the saw brand I have as well for my main chainsaw.
Notice I have it at an angle, the file holder also has angle designations to help stay with the direction needed to sharpen the tooth. Pushing away, keeping your file moving STRAIGHT ahead horizontal to the chain at the angle needed. DO NOT angle the file upwards or angle it downwards or you will just end up going to the hardware store to purchase your new chain if it takes you are chain to get it down. BE PATIENT!!!
When you have a dull chainsaw chain, you will notice your saw slowing down and catching on the log/branch. Your wood chips will be saw dust when the dull blade is cutting as well. You can gauge your chain's effectiveness by the size of the chips coming out after the wood has been cut by the tooth.
The easiest way to sharpen, unlock the bar-lock so the chain can move freely by hand, there are things out there that can be used to sharpen chains without the saw, but, you mostly see them at machine/blade sharpening shops.
The other way to sharpen is to use a electric sharpener. I will post a picture of one that I bought from a neighbor and plan on using later.
Remember, gloves, correct file and patience. Good luck & stay safe.