From the Start screen, tap the user account picture located in the upper-right.
To navigate to the Start screen, swipe left from the right-edge of the screen (to display the charms menu) then tap Start.
Unlock the Device
If necessary, press the Power button located on the top-edge (left of the volume key) to wake the device.
If necessary, swipe up to dismiss the lock screen.
If necessary, select the appropriate user account.