I assume you discovered the main discussion thread about this app? We have a few that a search will reveal. http://gmtnation.com/f23/torque-android-obd2-5536/
Recommend you post in that one if you have further questions.
Add the GM predefined set.
Settings>Manage extra PIDs/Sensors>(menu)Add predefined set>Pontiac/Gm/Opel/Vauxhall
All I would do (and have done myself) is add/name a profile for your vehicle and add the specifics - weight (off the web, unless you have scales), gas tank capacity, engine size, etc. Not much to it - just fill in the blanks.
On Torque on my phone, I have a profile for my wife's Impala, my TB and the in-law's Highlander.