is not working becuase this does not match your html structure.
this line basically says find the div that has a class ov tableborder and also has a class of postlinksbar.
in your html postlinksbar is inside of a div with a class of tableborder
so if you wan to set the id of that div to "topictext"
$("div.tableborder > .postlinksbar").attr("id","topictext");
and your a noob becuase you are learning, don't be so hard on yourself . So please read the posting rules in regards to subject titles. " im a noob" doesnt help much