type: dot -Tps filename.dot -o outfile.ps
If you want to use the dot renderer. There are alternatives like neato and twopi. If graphiz isn‘t in your path, figure out where it is installed and run it from there.
If you‘re using windows, check out the installed tool called GVEdit, it makes the whole process slightly easier.
Go look at the graphviz site in the section called "User‘s Guides" for more detail on how to use the tools:
http://www.graphviz.org/Documentation.php
(See page 27 for output formatting for the dot command, for instance)
http://www.graphviz.org/pdf/dotguide.pdf
