Switch from miles to kilometers
 

I am trying to figure out how I can make the above change on my own vs. bringing to a mechanic. I need this change in place in order to import my car to Canada as I am in the process of moving back from US.

This is from my owners manual.(I only copied the section on units) Since you didn't post what year HHR you have, not sure if yours uses the same procedure.

DIC Vehicle Personalization
Your vehicle has personalization capabilities that allow
you to program certain features to a preferred setting.
All of the features listed may not be available on
your vehicle. Only the features available will be
displayed on the DIC.
The default settings for the features were set when your
vehicle left the factory, but may have been changed
from their default state since that time.
To change feature settings, use the following procedure:
Entering Personalization Menu
1. Turn the ignition on while the vehicle is stopped.
To avoid excessive drain on the battery, it is
recommended that the headlamps are turned off.
2. Press and hold the information and reset buttons at
the same time for one second, then release to enter
the personalization menu.
If the vehicle speed is greater than 2 mph (3 km/h),
only the UNITS menu will be accessible.
3. Press the information button to scroll through the
available personalization menu modes.
Press the reset button to scroll through the available
settings for each mode.
If you do not make a selection within ten seconds,
the display will go back to the previous information
displayed.
UNITS
This feature allows you to select the units of
measurement in which the DIC will display the vehicle
information. When UNITS appears on the display, press
and hold the reset button for at least one second to
scroll through the available settings:
ENGLISH (default in United States): All information
will be displayed in English units.
METRIC (default in Canada): All information will be
displayed in metric units.
To select a setting and move on to the next feature,
press the information button while the desired setting is
displayed on the DIC.