To make creating tasks as easy and convenient as possible, you can create them from many different places on the calendar page. You can create a task using the button in the top right corner, but you can also create a task from the plan sidebar and immediately plan it into your calendar. When you're on the task list, you can create a task from the top right button as well.

If you're inside a course, which you can access by clicking on the course in the sidebar, the course will be prefilled for when you're creating the task. You can also add a new task right from the task list. I like this option a lot because it's quick, and if you're creating a task under a certain task category, the category will be automatically selected for you.