When people ask about finding flights, one of the recommendations is to use Google Flights. It's where I always start and I'm one of those who recommends it. However, none of us can do a complete "how to" due to the more specific nature of many flight questions.
Today I saw this detailed guide, complete with illustrations, to using Google Flights on The Points Guy and thought it would helpful to many. I hope it helps.
How to use Google Flights to find cheap flights and maximize your next travel booking. Here's the link.