Childrens Fantasy and Adventure Book

I want to commission a Childrens' Fantasy and Adventure book. It should be aimed at both boys and girls aged 11 - 13 and should include childrens characters as the main players and heroes. The book should be about 40,000 words long and should be delivered in word format. This is a work for hire contract and I will retain the copyright of the finished article. Please send samples of previous relevant work and also an outline of a potential story