When you create a gallery you can either publish or not publish it. Unpublished galleries can only be seen by you in your My Galleries editor.

If you don't click Publish your gallery will not be visible. You might think you created a gallery... and you did... but by not publishing it it remains hidden.

You can have photos that you move from one gallery to another. So you can take photos out of your "unpublished" gallery temporarily so someone can see them and then move them back again.