Don't know where to start? Try to start here!
Install Logon (you will have everything you need to develop a grammar). If you use Fedora, read this guide LogonFedora.
Yay, I love this series!!! Oops, just kiddin'. The Matrix is a tool for generating a toy grammar so you can play with it quickly.
If you want to use your grammar in production, you should use ACE. See this page for everything about ACE. Basically what you want is to download a copy of ACE from here, and then see this page to know how to use it. A version of ACE (may be older) is included with logon under the name answer and can be found at ~/logon/bin/answer.
NOTE: change virgo.dat to any name you want. Make sure you have a lowercase g for the first argument and uppercase G for the second argument. They are NOT interchangable.