Redirect url in plugin to somewhere else?

Redirect url in plugin to somewhere else?

I am using WP-SNAP Extended! v1.0.0 and I want to use this alphabetical menu as a sub-menu beneath my header. I managed to get the alphabetical menu in place, but now, if I click on a letter, it will show the posts on the page I am looking at and that is not good, because it overlaps the things that are already there. So you get a very chaotic website with many different content..
What I want to do is this: if I click on a letter, I want it to redirect it to a page where I output the posts that are with that letter. Now, it shows: http://somesite.com/test/?snap=C if I click on a letter. I want it to show http://somesite.com/test/?page_id=68&snap=C
How do I pull this off? I am using this function to get it: <?php if (function_exists('wp_snap')) { echo wp_snap(); } ?>