Slide your jack stand(s) into place near the jack, beneath a secure area of the vehicle's frame.

If you are raising both front or both rear wheels, place your jack stands to either side of the jack, near the wheels.

The purpose of the jack is to raise the vehicle, but the jack stand holds the vehicle in place. Be sure to place it in a safe spot that you know can support the weight of the vehicle, without it slipping off the jack stand.