[Plugin: Posts per Cat] Post Thumbnail Linking to the Post Permalink

Hello im trying to link the thumbnail to the post permalink, i guess i have to put the href with permalink in these lines but im not good in php.

$ppc_str .= wp_get_attachment_image( get_post_thumbnail_id($post->ID), $ppc_tsize ); }

can some1 help me with this please.

http://wordpress.org/extend/plugins/posts-per-cat/