redirect to new page and pass variables too? (fwd)

My previous question: I am collecting some data on a page - test.php, ($layer which is an array of names). If checkbox is checked that user wants to change drawing order, I should redirect the browser to page - "updateHTML.php" which has necessary script to do that. I achieved redirection using header(), but can't pass the $layer array with it. I tried something like: form.. input type hidden layer... header() but then the page isn't redirected since I get a warning that headers have been sent before the execu. of this line. What is the way to do this? I don't want to do include since it will put the contents of both the scripts on the same page. from the archives I understand I can't pop up a new window, fine if the page is displayed in the same window it's okay, but how to pass the variables? Thanks, -Pushkar S. Pradhan