When lifting a wall section into position, the bottom of the wall can slip across the floor deck, and even fall off. If you are short on help, a solution is to position the section as it lays flat, then drive duplex nails (with two heads) through the bottom plate into the floor. The nails will bend as you raise the wall to a vertical position. After securing, pull out the duplex nails.
Whenever possible, use a wooden or fiberglass ladder for outdoor work. Aluminum ladders could be dangerous around electrical lines. Also, stay away from the lines feeding power to your house.