Google Drive and Google Sites guides both mention how to create Google accounts, but it doesn't cover how to use one of the most fundamental parts of Google accounts, Gmail. The video below, which I did not create, does a nice job of showing you the basics of using Gmail. I wish the video was zoomed-in a bit more, but otherwise it's a good primer for the first-time Gmail users.
I saw this video Tweeted a few days ago and forgot to note who it was that Tweeted it. If it was you, please let me know in the comments.