Before you can start using SchemaSpy you must have installed two things in your system environment.
The easiest way to install Graphviz is to download the msi package from http://www.graphviz.org/Download_windows.php
Remember to add the folder containing Graphviz’s dot.exe application to your system PATH variable, eg.
C:\Program Files (x86)\Graphviz2.38\bin
- Linux, Mac OS
Please read carefully the detailed instructions on how to install Graphviz on your os version http://www.graphviz.org/Download.php.