PHP Fatal error:  Call to undefined function imagecreatefromjpeg() in C:\inetpub\dev2.mmf.mb.ca\plugins\content\jw_simpleImageGallery\includes\helper.php on line 105

After installing light box, I've got this message.
I don't know about PHP. What is this about?

Please, let me know. :'(
Thank you.

Oh I find what's wrong about me. Here is the solution.
www.phpca.net/phpBB2/viewtopic.php?t=462