HTML snippet

I’m not thinking straight and I’m sure the fix is very easy

I am trying to add a snippet in a page with a shortcode to a page. The snippet is just some simple html code to link to a php script where results of the php script would show on the page and the settings in the php file update every 30 seconds which causes the content to change

something like

div align center

http // xxx.com/subdir/display.php

/div