JQuery :: Access Elements From The Result Of A $.get Request?

I am currently working on an website which consists of 2 sites. Both have the same design (expect for the colors) and both sites have different navigation items (some are the same). I started the page in PHP with classes. Every site is a Site class which has an array of Content classes.Site->showNavi($section); prints out the navigation of the current site, with a navigation item for each Content class in the array. The active ($section) item is highlighted.Site->showContent($section,$subsection); prints out the content.

First i just wanted to use AJAX for the content section but then I realised that I could use it also on getting thenavigation and the content without reloading the page. So i searched the web and decided to use jQuery.

I started with the change site/design links and with the help of an tutorial i quickly managed to get these links work with following code:

$("#site_navi a").click(function(){ var site = $(this).attr('rel');
var cssfile = "/css/"+ site +".css";
var headerimg = "/img/"+ site +"/logo.png";
$("#site_css").attr("href",cssfile);

[Code]....

But it didn't work and after some testing i realised that i can't access the elements (e.g. a.navigationitem) which Igot from the request from "ajax_get_navi.php", because if i write down the navigation in the html code it works.

So, is there a way to get access to these elements? If not what do i have to change in the ajax_get_navi request to get access?