Activity Designer
The activity designer is an area in which you can assign activities to individual actions.
To open the activity designer, first hover the mouse cursor over the desired action. The action menu will then be displayed. Then select and click on the third icon shown in the screen-shot below. This will open the activity designer.
You can also double left click on the action, which will open the 'Edit action properties' window. Then press 'Activities'.
The designer for the activity will open. The area in which you assign activities is marked with a red frame.