Here's how to create a Task...
From the Board View:
From the Taskfeed tab, select the Board View.
Click to expand the sidebar.
Select an existing board from the sidebar.
Type a task on the bottom section of a chosen List and click Add.
You can then edit that task and include more details, as needed.
From the Taskfeed Main Menu:
You can also create a task from the Taskfeed tab by clicking and selecting which Board and which List that task should be added to.
If you haven't created a Board for that task yet, create it first. You can then go back and select this board from the lookup in the Task Create options.