First of all, you need to calm down and get chill pill.
Follow these steps and you will be okay;
- Go to Task page.
- Review the Task assigned to you.
- Update the Task status to 'Work in Progress'.
- Hit button Update.
The system will let your boss that you have reviewed the task and you are working on it. For every status changed in the task, the task assigner will get notification.
So if you have completed the Task, just go to the respective Task and update its status to Complete. Hit button Update as usual.