Hi Lilian,
On Notification Server:
Power Management Task
Go to Configuration > Server Settings > Notification Server Infrastructure > Task Server > Power Management Task Agent RollOut
You could use:
Task > Task Management > Samples > Restart
Add the computer you need to reboot
You have all options down there...
You could create your own Tasks by cloning this "Restart" and apply to your collections...through the Scheduling you will choose a collection as well as a schedule.
On Deployment Server:
Right Click on the computer you need to reboot Choose Power Control > Restart
You could also create your own job/task
check under the Job pane:
Samples > Misc Jobs > Power Control
You have a task called "Restart Computer" you could clone it or use it in a job.
Thanks