I am lost! How do I make a playlist?

Sorry, just came back to this after a year or so gone. Everything is still in place, all my songs and playlists and such. I know how to set up a playlist…but how do I add to it? But I cannot find a link to “add” the songs to a new playlist, or the edit feature to do that. And I cannot recall. Can someone explain the process to me me please?

Thanks for your input! Does this help: How to use Watch2Gether?