Here is the code I use to add a div or image or other element to just one page or category page of my WordPress sites:
This code will add a div with the id “featured_content” only on the home page:
<?php if ( is_home() ) { ?> <div id="featured_content"> </div> <?php } ?>
This code would add a div with the id “featured_recipe” to all posts in the category “recipes.”:
<?php if ( is_category('recipes') ) { ?> <div id="featured_recipe"> </div> <?php } ?>
This code would exclude “myimage.jpg” only on the Contact page:
<?php if ( !is_page('contact') ) { ?> <img src="myimage.jpg"> <?php } ?>
As you can see, there are many uses and ways implementations of this code. Let me know if you have any questions or need further assistance.