From the main Kanban view, you can click on the three dots on the top right corner of your task/To-Do do box. This will pull up the options to edit, delete, Start Work. Starting work will start a task timer that allows you to track the time spent on that effort and input it into your timesheet.
Once you start working, a timer on the top of your screen next to My Timesheet will start. No time will be tracked if you spend less than six minutes long on the task.