The thing that gets on the nerves of editors the most is that people submit work to their magazine without ever having even looked at the cover let alone read anything they have published. Visit the websites of the magazines you find, or go to the bookstore or library and browse copies of them. You can even read works published by some magazines in editions of The Best American Short Stories. The bottom line is -- do not submit work to journals without looking to see what they are about. Your work may not fit the aesthetic of some journals; other journals have certain time periods that accept submissions. Aviod embarrassment by researching and narrowing your venues.
After you have found and researched potential publishing markets, you will want to prepare to send your manuscript. There are a list of things you will need in every envelope you send out:
1.cover letter: a cover letter will contain the title of your piece, any "respectable" journal where you have been most recently published (Do not lie about this!!! Do not worry if you have never been published. Just leave it out if you haven't. We all must start somewhere.), and a thank you to the editor for reviewing your work. Also, ask them to recycle the manuscripts because you should not send your only copy and it runs a lot more postage to return it.