Display information only on a certain page

I am trying to have a piece of information appear on only the first page (the /wordpress/index.php page that displays the last x number of posts regardless of category) without appearing on the rest. I tried using $page = $_SERVER[‘PHP_SELF’]; but for some reason, the content of all the posts wouldn’t display if this variable was defined.
However, even if I got it to work, it doesn’t seem to be able to differentiate /wordpress/index.php from /wordpress/index.php?cat=2. Is there any php trick I can do that will have my information appear on only this first page that will work with WordPress?
Thank you so much for your help.