1) Check the "Time tracking" option at the workspace settings screen. The "Time tracking" tab will appear on the menu.
2) A clock icon will appear next to all notes. By clicking the icon you can log and categorize the hours spent on any activity.
3) When you create a To-do list, check the "Time tracking" option.
Now you can enter how much time has been spent on each task.
Click "Time" on the menu. From here you can see, edit and delete entries, use filters and export to excel files.