Using Images in PHP]

Hi List, I have PHP 5.28 with apache 2.2 How can i use images in PHP, i want to create a site where user will create their profiles. i heard something about Imagick class, but no idea how to use it, I mean do in need to install something extra(some extension or what). because when i write a code something like.

*1.    <?php
2.        $image = new Imagick('images/pkk.jpg');
3.        // If 0 is provided as a width or height parameter,
4.        // aspect ratio is maintained
5.        $image->thumbnailImage(100, 0);
6.        echo $image;
7.    ?>

*I get the error on line # 1, that means i am not able to create the object for I magick class. i think i need help in installing configuring the Imagick extension. please suggest. praveen.,