Anybody know where I can find this and how hard it is to install? I need it to run PhotoPost on my website but it has not yet been installed yet. If it's easy to get and install I will do it myself to get PhotoPost back up.

mogrify is part of ImageMagick, http://www.imagemagick.org, and the easiest way to set that up is through rpm

http://www.photopost.com/howtoinstall-php.html

There are the links to download ImageMagick, and follow that step by step, and you will be running with photopost again in no time.