New user question for Mac OS MP3TAG

I'm a brand new user of mp3tag on my MacBook Pro. I know that this seems a stupid question, but it is NOT covered, so far as I can tell in the FAQs (it's probably too basic). I've dragged & dropped some files to the mp3tag work window; I've added the proper artwork (downloaded from the internet); I've saved my files (Command-S). Now how do I close the files that I've edited so I can open some more? I've tried Escape, Command-C, and looked in the menus and the help. Nothing there. If I use the Delete key, it undoes the edits that I've saved. So, pardon my ignorance, but how do I close edited files?

Thanks - Boomzilla

You simply load the next ones.