Navlink images

I have looked all over, I’ve also tried myself..
I building a theme and want to include images in the nav from the themes dir. So how do I put these two together.

posts_nav_link bloginfo(stylesheet_directory)

everything I’ve tried get errors.

Here’s what I got:

<?php posts_nav_link(' ','<img src="'.'bloginfo('stylesheet_directory')'.'/images/next.jpg" alt="next" border="0" />','<img src="bloginfo'.'('stylesheet_directory')'.'/images/prev.jpg" alt="prev" border="0" />'); ?>