I have an application where I am required to resize the uploaded image files and store them. Can anybody help?

Google is your friend, maybe this snippet might help you:

http://www.weberdev.com/get_example-3938.html

or

http://4wordsystems.com/php_image_resize.php

by image resizing do you mean Thumbnailing? If yes I can provide you a good class of Thumbnailing which can create good quality thumbnails.

Let me know

The usual way is to use the GD library's imagecopyresampled() function. ImageMagick is also available. You'll need at least one of these extensions available to PHP first.