Installation is very easy, basically extract the code from GitHub and copy it into a directory accessible from the web, point your browser to the directory and you should be ready to go.
The different parts of the application are:
Simply type your query into the text box and click on the execute button.
This is an information page, so simply accessing is enough to get all available information.
Write your code into the code editor or load a pre-existing script and edit it. You can click on execute as many times as you need to see the internals of the executions.
In order to simplify the scripts, there are a set of variables and functions you have access to in your scripts:
Just copy the script into the testcode directory and it will be detected automatically.