For general information, such as how to navigate the operating system, personalize the Start screen, utilize apps and customize settings, refer to the Windows 8.1 Tutorial.
Don't attempt to insert the SIM card while the device is powered on. Doing so may harm the SIM card and/or the device.
Ensure the device is powered off.
From the top edge of the device, remove the card tray. Utilize the insertion/removal tool to unlock the tray by inserting it into the provided slot (figure 1) then remove the tray (figure 2).
With the gold contacts facing down and the notch located in the upper-left, insert the SIM card into the tray as shown. Ensure that the card is properly seated in the tray with the front of the card under the notch.
Insert the card tray. Press in on the tray to lock it into place.