Tasks are on the left. You can add subtasks using the "subtask" button or by dragging a task under another one.
Task title should be short and easy to read, as they'll show up whenever someone is working with them (in the activity feed, in budgets when time is tracked, mentioned inside of other task's chats, and more.)
There's a chat for every task or subtask in Turtle. In the example above, I have the "Request a new catwalker" task open, with it's Activity feed & Chat open to the right. I've added designs, notes, and a due date right inside chat. This way, any team member can quickly see how this task is coming along and what requirements are being used.
Chat is where requirements, designs, questions, updates, and feedback should go.
If you notice a chat getting too long to follow, consider creating a subtask or a new task, A task's activity and chat that has gone too long may be an indicator of a task that is getting dragged out beyond original plans.