If you're new to chainsaws this video should help you learn how to buy the right size chain the first time. Links to products and articles below.
I was not paid to make this video or promote any specific products. However, if you do click on the Amazon affiliate links below and purchase something on Amazon the channel will receive a small commission paid by Amazon. No extra cost to you.

Steel Bumper Spikes (Felling Dog) for Small stihl saws. (For saws that just have the plastic spikes. You need to be careful threading in the screws (go slow with a little oil and be careful to not crack the plastic), but they work fantastic once they're in): https://amzn.to/2REpXGw

Oregon Chainsaw Chains (Cheaper than Stihl and cut just as good): https://amzn.to/2ZQU4iK

Safety helmet/ear protection/face guard: https://amzn.to/2FR0Z4o

Chainsaw chaps: https://amzn.to/2ZNhSnC

Articles on chainsaw chains:

https://sawfaq.com/types-of-chainsaw-...

https://www.oregonproducts.com/en/fin...

http://www.madsens1.com/bnc_teeth_typ...