Open the Tasks list that has your task.
In the Content pane, click on the task that you want to change, or select the task and click Edit on the toolbar. The task page opens.
Make the changes to the task information.
Click Save when your changes are complete.
Two ways to mark tasks as complete:
Check one or more tasks to be marked complete. Right-click on a task line and select Mark as Complete. The % Complete is changed to 100%.
Check one or more tasks to be marked complete. Click Mark As Complete on the toolbar.
The task information remains in your tasks folder.