I have to add drawing facility to my php webpage, so that users can draw there own pictures online, someone please help me to solve this problem, thanks in advance
You can use GD library to accomplish this type of application Visit http://php.net/manual/en/book.image.php for more information
For front-end you can use java script to get the user drawing coordinates which can parse in GD library to get the job done.
I believe you need to look into the canvas element for your project; this is not something you will be able to do solely server-side (using PHP).