Essay Sources

I am writing an essay about the effects of technology on daily life, and I need to include sources to support my points. I have found several articles, but some seem too old or have no clear author. While searching for guidance, I came across English academic writing service, but I want to learn how to choose sources myself. Should I mainly use recent articles? How many sources are enough for a short essay? I would appreciate a simple way to check if a source is strong enough to use.