The Westcott Mini Apollo is designed for flash units that are mounted on a tripod. By attaching the Westcott Mini Apollo to the flash unit, the light from the flash unit is diffused. The light from the flash is diffused and therefore softer and more uniform. And you have less trouble with cast shadows!
Place your flash unit directly in the Westcott Mini Apollo, and turn the head of the flash unit towards the back of the Westcott Mini Apollo. This way you get very nice indirect, evenly distributed light!
Westcott Mini Apollo Softbox for Speedlights 16x16 inches