Contributors are people who have made a vital contribution to an eBook. Most books will only have the Author as a contributor. Illustrated books may also include the name of the Illustrator, and collections of short stories or articles may include the Editor as a contributor.
Do not use the contributor field to list the names of everyone who has helped you with your book; use the Acknowledgements page of your book for this.
The contributors will be listed on the website listings of your book on different distribution channels. These listings will not necessarily list the contributors in the order they were submitted.