8. Click on the "Info fields" tab and then on the "Add a field" button.
9. Enter a name, select to display or not the title of the info field (the title is displayed differently from the text field content).
10. Select Display Mode options (at least one to show the info!). Usually one can choose rollover (information is displayed in a tooltip on mouse enter the activity cell in the Schedule) OR Inside (info is displayed inside the cell, under the title or the time, only if the cell is large enough to display the info. If it's not, the info will be displayed in a tooltip on mouse over the cell). So it is better not to choose both inside and Rollover.
11. Select an access group.
12. The field is display
13. You can see it by rolling over the activity. If "Image in tooltip" is set to yes, the image is also displayed in the tooltip.
You can also manage fields from the fields list view.