+ return """
+<p> <i>Welcome to zcommit.</i> </p>
+
+<p> zcommit allows you to send zephyr notifications by sending an HTTP
+POST request to a URL. Currently zcommit supports POST-backs from
+github. If you would like it to support another form of POST-back,
+please let us know (zcommit@mit.edu). </p>
+
+<h1> URL structure </h1>
+
+The URL you post to is structured as follows:
+<tt>http://zcommit.mit.edu/$type/$key1/$value1/$key2/$value2/...</tt>.
+So for example, the URL
+<tt>http://zcommit.mit.edu/github/class/zcommit/instance/commit</tt>
+is parsed as having type <tt>github</tt>, class <tt>zcommit</tt>, and
+instance <tt>commit</tt>. Using this information, zcommit figures out
+how to form a useful message which is then sends as a zephyr.
+
+<h1> Github </h1>
+
+Set your POST-back URL to
+<tt>http://zcommit.mit.edu/github/class/$classname</tt>, followed by
+any of the following optional key/value parameters:
+
+<ul>
+<li> <tt>/instance/$instance</tt> </li>
+<li> <tt>/zsig/$zsig</tt> </li>
+<li> <tt>/sender/$sender</tt> </li>
+</ul>
+"""