[galaxy-dev] Venn diagram example data

Dear Galaxy list, I am interested in Galaxy Charts visualization.But venn diagram confuses me when I upload my tabular data, it seems venn diagram need one column observations at least, actually I don't clear what should be contained in the one column observations. So is there any venn diagram example data or usage for this charts plugin ? Sad to say I am not good at JavaScript :) Thank you very much. Regards, Steven