I have a custom attribute yes/no and what i want to do is on the product detail page of my magento site show or hide an image based on wether the value of this attribute is
If your attribute was called, say, show_image then you read it back like this:
show_image
<?php if ($_product->getShowImage()) : ?> <img .... /><!-- PUT WHATEVER ELSE HTML YOU NEED HERE --> <?php endif; ?>