Help adding to “The Loop”

I am trying to add a bit of code to the loop.php using k2. This is the code I want to add:

<div id="sb"><a href="http://www.stumbleupon.com/submit?url=<?php the_permalink(); ?>&title=<?php the_title(); ?>" title="stumble"></a></div>

I know where I want to put it, it’s just that nothing happens when I add this, nothing at all. I’m not sure if the <div id= part is right, I have a section of css I made for this using:

#sb a{
and
#sb a:hover{

and I went off of example to add this code. Can anyone help me with what I need? I am new to k2 and using the loop so I apologize if it’s an obvious answer.