You create a GraphGist by creating a GitHub Gist in AsciiDoc and enter the URL to it in the form on this page. Alternatively, you can put an AsciiDoc document in Dropbox and enter the public URL in the form.
This GraphGist shows the basics of using AsciiDoc syntax and a few additions for GraphGists. The additions are entered as comments on their own line. They are: //console for a query console; //hide, //setup and //output to configure a query; //graph and //table to visualize queries and show a result table.
Click on the Page Source button in the menu to see the source for this GraphGist.