Where do I put the supports when working underneath 2006 Chevy Malibu? I need to change my rear shocks

Look under the car - you'll see 2 long metal rails ( the frame rails) . Support each side with a 2 ton minimum jack stand fully extended approximately one foot ( 12" ) in front of the rear wheels. Now use your jack ( preferably floor style ) to lift one of the rear wheels to relieve the pressure on the shock. Remove fasteners securing the shock, then remove and replace the shock. If the new shock has a plastic strap attached, do not cut this strap until you have mounted the shock on the vehicle. If you do not have an exposed frame rail, you'll see a "pad" in front of the rear wheel close to the outside of the car - it should be about 10 inches in from the pinch weld and about 12 inches in front of the wheel. Use this pad for the stand and lift the vehicle by the c shaped bar that goes from 1 rear wheel to the other. Do not support the car with just the jack -it could let loose and drop the car on you.
Hope this helps!