The title of the book is 'mindfulness approach anger management,' with a subtitle, 'an eight week program.' Somewhere on the cover also should be the author's name, Craig Mollins, and also the text: "including 2 hours of audio exercises."
The feel of the cover should appeal to a mainstream anger management audience, but should not have any anger in it at all. Rather it should feel good and provide relief. People should feel good and hopeful when they look at the book cover.
Even though the concept involves mindfulness, it should not be new age or spiritual or 'love and light'. It needs to speak to a mainstream audience the concept of mindfulness and at the same time somehow anger management. The anger management aspect could be subtle, or it could even be anything with the idea of self improvement or personal development. But it needs to be strong and trustworthy
Anger management audience is skeptical and, obviously, angry, so they are sensitive to anything flaky or manipulative. Thus the cover needs to be direct and clear, and yet it needs to portray some feeling of hope and progress, that this Ebook is going to help them.
The book cover needs to communicate its message clearly and make an immediate impact, because it is an Ebook and people will leave the website or stay, all depending on if they get the message conveyed by the book cover.
The mindfulness element includes the ideas of space, presence, clarity, gentleness, and strength.
I don't have any suggestions for images. But there are many potential ways to communicate mindfulness, if it contains some feeling of the elements just mentioned.
If you google mindfulness images you will see a lot of zen gardens and sitting meditators and gongs, all of which are possible, but I think not great choices. They tend to make people think of spirituality, which has a stigma attached to it and will put off most people.
Instead, the cover should convey trustworthiness and professionalism, and yet at the same time it needs to communicate the openness and effectiveness of mindfulness.