You can add hours of employees that haven't worked in 3 ways:
You can approve hours of your team every night at the end of your shift through the Soigné app.
If someone worked that wasn't on the schedule - and therefor isn't in the list with employees to approve hours for - you can add their hours through the [+ Add hours] button at the bottom of the task.
Alternatively you can add hours from the 'Approve hours' task from Soigné in your browser.
Finally, a third option is to add hours from Schedule → Worked hours → Add worked hours.