The first line of the spreadsheet should contain the series titles. The second line of the spreadsheet must contain the type of series’ data. You may use one of six data types: string, number, boolean, date, datetime and timeofday. The other lines need to contain data values according to the data type chosen.
Choose “CSV (comma-separated values)” type from select box below “Get a link to published data” sub header and copy link to the published spreadsheet at the text area below.
After you’ve published your spreadsheet, create a new chart or edit existing one and go to the second step, which allows you to upload your CSV file. Expand the “Upload CSV file” sidebar menu and click on the “From Web” button. Then enter published link into prompt dialog and click “Ok“. After you have entered the link, it will be automatically uploaded and a chart preview with the data will be updated.
Now your chart will use this spreadsheet as data source. Each time when the chart will be displayed, it will fetch data from this spreadsheet. Don’t forget to republish your spreadsheet each time you make any changes to it.