How do I program a Power Expander. I know it is kinda the same as programming motors.
A power expander does not need programming (unless you want to read the battery voltage from the status port). A power expander is placed between the cortex and motor to allow the motor to be powered from a second battery.
Check out the “installation” tab on the product page.
http://www.vexrobotics.com/vexedr/products/accessories/electronics/276-2271.html