The 'Quick timesheet' feature is available from within tasks that are set to allow timesheet entry. Open the task that you are working on and click the 'Quick timesheet' button.
This opens a window where you can enter the phase (for a job level task), charge code, time spent and work done notes. The date defaults to the current day's date. From this window you can change the kanban status on the task and/or mark the task as complete. Click 'Post' to enter the timesheet.
Note: You can restrict the creation of quick timesheets from a task to the task owner only or allow it for any user. You can also disable this feature. To change these settings go to Settings, File Maintenance, Task Types. Open the requisition task type, under 'Can create timesheet' select 'Owner only', 'Anyone' or 'No'.
The Timesheets tab on the task will only show timesheets created using the quick timesheet function on that task.