To create a task from a post, go to the post and click the tasks icon:
After you have clicked on the Tasks icon, you will be redirected to a new window with a "New Task" box:
Here you will notice that the original text from the post you chose to convert has been added to "description". Simply choose a new title and category, as well as a due date. You can also assign the task to someone or you can choose to complete it yourself. Click the blue "Add" box to convert the post into a task.