PHP RSS XML链接到Items并显示部分项目

I am struggling with RSS/XML code here. I want to read a blogger (blogspot) RSS feed. My PHP knowlegde is ok, but maybe this is to much to ask from myself.. Ik hope you guys are a lot smarter than me.

I already have some code :

Code of the items

    <?php
$post = $_GET['post'];
$url = "http://mrexcelxl.blogspot.com/feeds/posts/default?alt=rss";
$rss = simplexml_load_file($url);


if (!isset ($post)) {
$items = $rss->channel->item;
foreach($items as $item)
{
$title = $item->title;
$link = $item->link;
$description = $item->description;
echo '<h3><u>'.$title.'</u></h3>';
echo '<p>'.$description.'</p>';
}


}

if (isset ($post)) {
$item = $rss->channel->item;

{
$title = $item->title;
$description = $item->description;
echo '<h3><u>'.$title.'</u></h3>';
echo '<p>'.$description.'</p>';
}
}



?>

Code of the menu

 <?php  

// Show number of items  

$items = 10; 


// Load rss
$rss        = simplexml_load_file('http://mrexcelxl.blogspot.com/feeds/posts/default?alt=rss'); 


// show last items  
for($i=0;$i<$items;$i+=1)  
   { 
   echo "<a href=?post=" . $rss->channel->item[$i]->title . "> <h3>{$rss->channel->item[$i]->title}</a></h3></a><br>";  

   }  

?>

So.. I'd like to: Show about 250chars of 10 items on the webpage, with a 'read more' button. If click -> show full item. I'd like to show all the items in the menu. If click -> open item.

Very very easy I though.. but no...