Use the Tasks feature to add a checklist of tasks. To access them, open the ✔ Tasks popup located in the Left Sidebar.
Tasks are tied to and will switch as you switch between projects.
In the Tasks popup, click the ➕ Add New Task icon.
Write some text and press Enter/Return to keep adding now Tasks.
Hover over a task, and click on the 🗑 Delete button on the right side of the task entry.
Click and hold the 3-line icon to the right of the Task and drag.
Toggle the Show Completed option to hide or show finished Tasks.