To add real-time data feed to your chart:
1. Go to spreadsheet mode (double click on chart) and press "Load data"
2. Choose “Connect live data”
3. Enter URL from Google Spreadsheet or JSON feed.
Keep in mind that Google Spreadsheet must be published to the web (see the File menu in Google Drive). Data in the feed should be in a JSON array format with sheets as outer dimensions (having a similar structure as in infogr.am spreadsheets), followed by rows and columns.