Jo, I'm not exactly sure what you mean.
If you mean you can't find either an email, or snail mail addy, then yes, go to the website. Usually there's a "Contact Us" thingee to click on. If it's a magazine, sometimes the various editors will be listed and their email addys. Sometimes they have their own email form right there. Snail mail addys can often be found too either by clicking on "Contact Us" or "About Us." Be sure to check around to see if they have writer's guidelines posted on the site too.
Just in case you meant "what the heck is a query?", it's a short pitch on a story idea that includes your creds on why you're perfect for the job. Or, a short description of a finished piece with your creds etc.