Using the Checklist function you have the ability to create a subtasks list under each main task. 

To add a new item to your task checklist, please, follow steps shown below:

1. Click on the "Plus Button" on the bottom of the task cell (if you are doing it from the iPad, please, make sure you are in the 'Editing mode'):

2. Here you can enter the name of an item you want to add:


3. You will now see the checklist is already created, the cell will show you completed and uncompleted subtasks:

4. If you will click on the checklist button, a window will appear. Here you are able to mark your subtasks as complete:


You can even drag and drop items by clicking and holding the button on the right side to reorder item if needed:


To delete any item, click on the 'Red Button':