How to edit a photo.
Within the admin menu choose the option “content”.
Within the “content” menu choose the “Media” tab. Then hover over the photo you’d like to edit, and click “view details“.
On the resulting pop-up choose the “edit” button.
This will lead you to the image editor. Make changes as necessary, and choose either “Save” to overwrite the current photo, or “Save as copy” to leave the original intact.