Your organization may allow regular users to schedule a resource for maintenance. Some organizations only allow dispatchers or SYSOPs to schedule maintenance. If you are a regular user, you may be permitted by your organization to make an immediate maintenance schedule for cases where you find that the resource is unusable. These schedules must start immediately and for no more than 48 hours in duration.
You may see a menu called 'Make a Maintenance Schedule' just below the main menu row. Click on this and schedule much the same as a regular user to scheduling an aircraft for a flight.
If you do not see the button/menu described above, then you are not authorized to schedule maintenance.