Note: As of writing the only version of ImageMagick I can get to work is ImageMagick-6.8.0.8.tar.gz so grap that tar file from ImageMagick

Cd to the directory where you downloaded ImageMagick then run the following to install ImageMagick.

tar zxvfp ImageMagick-6.8.0-8.tar.gz
cd ImageMagick-6.8.0-8
./configure
make install clean

Finally test if things are working as intended.

/usr/local/bin/convert logo: logo.gif