The only way to do this in PHP would be to use a location header like this:
Code:
header( "Location: http://www.yoursite.com/new_page.html" ) ;
The only downfall with this method is that the line above should appear before anything is output to the browser (meaning that you cannot display a message before the user is redirected).
If you want to display a message and then redirect the user after some time, you have to use a JavaScript solution.