Coutinhor
add the following to the top of your page
<?php
/*
Template name: [template name here]
*/
?>
Save the file as a php extension.
Use an FTP client (Filezilla, FireFTP, etc) to upload your php file to your site’s theme folder. Usually sitename.com > wp-content > themes > themename
Refresh the WordPress side and the page template should show up in the drop-down list.