Inquiry essay is a type of paper that investigates into things that you don't yet know but want to find out about. Word "inquire" means to to ask for an information, or to try to find an answer to questions you don't yet know.
First, you have to think what you know about the topic that you're going to write about. Evaluate your knowledge and the things that your audience, the ones who will read your essay, know on your topic. What do you have already know and why do you want to learn more information? What is so interesting about your topic?