Grouping tasks makes administering large projects or long task lists much easier. To create groups of tasks or sub-projects, select the 'Custom order' or 'All' View.
Click the drop-down symbol next to the 'New task' button and select 'New group'. Enter the name of the group and press return.
To add your first task to the group, select the group by clicking on it's title, and press return, or press the '+' symbol highlighted above.
To insert a new task into a group, click on any of the tasks in that group and press return. A new task line will be inserted below the one you clicked on.
If you want to move existing tasks into a group, hover your mouse over the task, then drag and drop using the icon with the three horizontal lines.