If you use just one single.php for all singles and you want to display something on a single view only in one category, use the condition 'in_category()', this tests if the current post is assigned to any of the specified categories.
Anywhere in single.php you can add this:
<?php if ( in_category( 'blogs' )) { ?>
here your code or explanation
<?php } ?>
try this code just as it is in single.php and look if you find "here your code or explanation" on your blogs category single page, if it works think about what to put in there
more about in_category here:
http://codex.wordpress.org/Function_Reference/in_category
btw: you had problems to post - I found your posts in the spam filter, too many links in there ...