Was this based of another existing artwork? It is pretty, but if the design did not come from yourself, you should always cite your sources. This is so that your audience have all the information they need to form an opinion about your works.
https://www.deviantart.com/picolo-kun/art/-280-Atlas-493347892
No problems. No one is perfect :) We can always be given opportunities to improve on ourselves.
Copying as a way to learn is valid, but you should ALWAYS cite your sources so that there is no misunderstanding for your audience. Coming up with the designs for a picture is often what makes a picture beautiful.