If a book has an editor, you will be able to find their information in the opening pages of a book before the table of contents or first chapter. This information is often on the copyright information page, although the editor’s name may be listed in the acknowledgements or on the title page instead. If a book has no press or an editor is uncredited, you may need to do some research or contact the author to get editorial information. To contact an editor, contact their publishing company or use their personal or professional website to reach out to them. Remember to always be cordial if you’re planning on a getting a letter or phone call back!
I've done four covers through Ebook Launch for two different series, and they've knocked it out of the park every time. In one case they were creating brand new covers based on a high-concept mashup idea. In another, they were following in the footsteps of a different designer, who'd already established the look for an existing series. Both times -- whether coming up with something totally new or sticking to an established style -- they did fantastic work. I love my Ebook Launch covers!