It sounds like you're tankilg about query letter and not a cover letter. There are many ways to write it. You can say something like [A couple of paragraphs about your novel]NOVEL NAME is an Urban Fantasy complete at 60,000-words, and is the debut novel of [your name]. In publishing, titles are written in all caps. You want to mention that it's a fully complete, and edited novel. Debut means it's your first novel and that you've never been published. The word count matters because if your novel is too long or short then that means automatic rejection, so they won't waste time requesting a partial or full manuscript. If you don't have any writing credentials or anything that's been published in a real magazine or book or newspaper then this will be pretty short. You don't need to give your age unless someone specifically asks for it or if someone offers to represent you, then you need to disclose your age. It's probably best if you leave the personal details as the last paragraph and start the query letter with what your book is about. Always address the agent by name and don't send the same e-mail to many agents; each agent should have their own, separate e-mail. You can find examples of query letters over the Internet.