Read more button in my blog with php
I'm new php.  
I want your help.  
I've a blog, In index page it's show all post. I want to a 'show more' button/text when my post message are 24 characters and if i click 'show more' button/text then it's should be show my full message to another page. My index page code are bellow which is get every post from the database:

    <?php
    include "db/db.php";  
    $upload_path = "user/manage/userpostimg";
    $sql_2 = mysql_query("SELECT * FROM user_post ORDER BY post_id DESC");
    while ($rel_2 = mysql_fetch_assoc($sql_2))
    {
    $idu = $rel_2['post_id'];
    $subu = $rel_2['subject'];
    $imgnameu = $rel_2['img_name'];
    $imgu = $rel_2 ['image'];
    $msgu = $rel_2['message'];
    $dateu = $rel_2['date'];
    $posteru = $rel_2['poster'];
    $cat_nameu = $rel_2['cat_name'];

    echo "$subu" . "<br/>";
    echo '<img src="' . $upload_path . '/' . $imgnameu . '" width="75"  />  ';
    echo "$msgu" . "<br/>";
    }
    ?>
How can i do this? Can you please tell me, that will better for me.
Thanks in Advance. 
Read more button in my blog with php
===

I'm new php.  
I want your help.  
I've a blog, In index page it's show all post. I want to a 'show more' button/text when my post message are 24 characters and if i click 'show more' button/text then it's should be show my full message to another page. My index page code are bellow which is get every post from the database:

    <?php
    include "db/db.php";  
    $upload_path = "user/manage/userpostimg";
    $sql_2 = mysql_query("SELECT * FROM user_post ORDER BY post_id DESC");
    while ($rel_2 = mysql_fetch_assoc($sql_2))
    {
    $idu = $rel_2['post_id'];
    $subu = $rel_2['subject'];
    $imgnameu = $rel_2['img_name'];
    $imgu = $rel_2 ['image'];
    $msgu = $rel_2['message'];
    $dateu = $rel_2['date'];
    $posteru = $rel_2['poster'];
    $cat_nameu = $rel_2['cat_name'];

    echo "$subu" . "<br/>";
    echo '<img src="' . $upload_path . '/' . $imgnameu . '" width="75"  />  ';
    echo "$msgu" . "<br/>";
    }
    ?>
How can i do this? Can you please tell me, that will better for me.
Thanks in Advance. 