Help with CSS Selecter

Hi, my website is http://tungnk1993.byethost17.com/8chuyen/wordpress/

Basically the relevant structure is:

<div class = "contentwrapper">
	<div id="content">
		<div id = "news">
			<div class = "post">
			</div>
			<div id = "older-posts">
				<a></a>
			</div>
		</div>
	</div>
</div>

Currently my setting is this :
Content Selecter #news
Nav Selector #older-posts
Next Selector #older-posts a:first
Item Selecter #news .post

Any help is appreciated. Thank you

http://ww.wp.xz.cn/extend/plugins/infinite-scroll/