You can access the Device Lock feature by selecting Settings --> Device Locks. Once on the device lock page, you'll want to select the +Add a New Device Lock button.
You will need to enter a name for your device lock and assign it to the appropriate employees. If you are ready to assign the device lock, click Save & Assign the Device. If you do this, you'll notice back on the device lock setting page that a new notification is available.
If you simply need to adjust the employees assigned to a device lock or perhaps make it inactive, you need to select Save.
Please note: You will need to setup the device lock FROM the device you're looking to lock your employee to. If you want to lock an employee to their computer at work, you will need to setup the device lock from that employees computer while on your Admin account.