A recent discussion on the Yahoo CW list reminded me of some advice I posted there once about the meaning of the term "no unsolicited manuscripts." Here's the post:
"No unsolicited manuscripts" does not mean you can't send something to these publishers. (Those who are truly closed will say something like "Not accepting submissions.")
"No unsolicited" just means you must send them a one-page QUERY first. If they like your idea and feel your book is a possible fit for their list, they will reply to your letter inviting you to send your manuscript. Then, WHEE! Suddenly you're sending a solicited manuscript.
I understand your confusion. I used to think that "no unsolicited" meant they actually only approached famous people and solicited manuscripts from them. Sounds incredibly naive of me now, but that's honestly what I thought.
You do not have to be previously published or famous or have any sort of contact in the industry for a publisher to take your query seriously. I got many "yes" responses to my queries early in my career, when I didn't know a SOUL in "the biz."
If they wish to see your manuscript based on your query, they'll write back and tell you their company procedure for you to send the now-solicited manuscript. Usually that means marking your envelope as "requested material," or something along those lines.
(Now I know what some people are thinking: "Why not just mark the envelope "requested material" FIRST and send it off? Answer: Editors have good memories. They will not only know they did not request a falsely marked manuscript, they will also remember the deception if you try to contact them later, even if you do it "by the rules" the 2nd time.)
There is lots of information online and in books on how to write a good query. It's a form of marketing yourself. The query serves as a first glimpse of your writing style, so it needs to have personality and yet be professional. I know it seems hard to convey the quality of a million-times-revised story in a li'l old query, but trust me, editors are well-trained to spot potential in a query. Plus, you can always insert a small excerpt from your manuscript so they can get a sense of your style as well. Do a search online or in an online bookstore on "How to write a good/strong query," and you'll hit a mother lode of helpful information.
You might want to read another blog post where I published the query that sold my CROCODADDY to Sterling editor who had never heard of me until she read the query. Read that HERE. I have since sold other books to Sterling, so my query was the start of a great, long-lasting relationship.