ImageMagick does not come *standard* on servers; if you're in a shared hosting environment, make sure the path to mortify and convert are set properly (in your paths section of your control panel). If it isn't installed, your webhost will need to install it for you.
GD itself has to be compiled into PHP; again, if your webhost does not have this you'll have to have them install it for you. You can see if it is installed by creating a phpinfo page:
phpinfo.php:
Look for a heading of "GD" and post the result; if you don't see one, then it isn't installed.
