Ask your administrator to enable it for you using the Installation Ask your administrator to enable it for you using the Installation chapter of the manual.
If you tried this example and it didn't output anything, or it prompted for download, or you see the whole file as text, chances are that the server you are on does not have PHP enabled. Ask your administrator to enable it for you using the Installation chapter of the manual. If you're developing locally, also read the installation chapter to make sure everything is configured properly. If problems continue to persist, don't hesitate to use one of the many PHP support options.