Include it in your header and it's ready!
Brosho is a development tool and therefore it should be no hustle to include it in your project and run it.
Given you have a directory js, copy and paste the brosho directory to it. Path to brosho now should be /js/brosho/jquery.brosho.js. If your path is different please see the Custom Usage section.
Now just include the Plugin along with jQuery in your header:
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4/jquery.min.js"></script>
<script type="text/javascript" src="js/brosho/jquery.brosho.js"></script>Done! Now you got the brosho editor included with the default settings. Play around with it on this site.