I've put a lot in this blog for writers. This is the $64 question: How to get published.
1) Write well. (refer to all the ways I said to do that in this blog's posts, and get info from others too.).
2) Research your target (learn about the industry, so you know what you're doing).
3) Write a great query letter (Jen Garsee is going to do a guest post on this topic).
4) Write a great synopsis.
5) Don't rush the process, wait until you have your best work ready to go.
Most querying is done online these days, keep in mind that if you are querying in a country other than your own, if you send an attachment change the paper size to match the common use in that country. They might want to print your synopsis and pass it around the office because they love the concept of your ms.
Well, that's it in a nut shell.