jules_thestar on "error in plugin development"

hi am new to plugin development, i have red few books.I would like to develop my first plugin for social sharing,but am getting few errors in following code.

<?php
   $social_sharing_toolkit = new MR_Social_Sharing_Toolkit();
   echo $social_sharing_toolkit->create_bookmarks();
?>

For a better look at a plugin developed with this functionality, look at celibatemonk http://www.celibatemonk.com/

Anyone know what is causing this?
thanks in advance