They should help. But, you could always draft one up and post it in the Showcase / Brainstorming sections for help to improve what you already have. (There are already a few on the site but I can't remember exactly where)
Oh, honey, there are so many books dedicated to just this subject... squirming around to look at my writing reference library I'm looking at 3 titles at first scan alone, and my library is far from comprehensive.
First question session - You say "novel series." Are you talking about a query letter for the entire series? Is it completed? Or are you talking about a book proposal for the first book in a proposed series that is not yet completed? These will all change the landscape of what you want to say dramatically.
These days the submission process tends to follow certain steps. The first is the query letter sent to an agent or an editor (usually an agent). This letter should be attention getting, yet professional and to the point. It should never exceed 1 page. You should always make absolutely certain that you are sending this letter to the right person, and never ever address it to "Whom it May Concern." Yes, there are whole books & blogs written on just writing queries. Yes, I recommend reading them.
Following a positive reply to your query comes the book proposal in whatever form the agent or editor in question's guidelines indicate. Again, there are tomes written on this subject. The book proposal comes in several parts - the cover letter, the outline, and the manuscript. According to the guidelines, the parameters of these parts may differ from agent to agent, but the usual rule of thumb is that the cover letter should never exceed 1 page.
Good luck, and go see what books your local library may have on writing cover letters and queries. You may be surprised. Also, make sure you browse about online and see what agents and other authors have to say on their blogs.