Your battery has been partially charged at the factory. If the device indicates a low charge, do the following:
Connect the charger to a wall outlet.
Connect the charger to the device.
When the device indicates a full charge, disconnect the charger from the device, then from the wall outlet.
You do not need to charge the battery for a specific length of time, and you can use the device while it is charging. If the battery is completely discharged, it may take several minutes before the charging indicator appears on the display or before any calls can be made.