This is a worldwide collection, so anyone in any country may submit their art. However, you'll need to be 18+ to submit. Selected artists for the Tribute collection will have their work included and credited in the book, which was announced at NYCC last year, and should make its first appearance at San Diego Comic-Con 2013 as a special, limited-edition hardcover.
If you're an artist and you'd like to see your Warcraft-inspired work make its way into print, this is an opportunity you don't want to miss. For more information, including rules, guidelines, and submission information, head to the official World of Warcraft Tribute website.