High key outdoors is the same as high key indoors, EXCEPT that you will need to balance with ambient light. Think of it as two separate exposures, one from the ambient, natural light, and the other from the flash(es).
You'll set the aperture for the flash exposure, and then set the shutter speed for the natural light exposure. The shutter speed should be "correct" for the natural light exposure, so the background doesn't look weird and dark. Your aperture controls the amount of flash the camera sees, since the strobe much faster than the shutter, shutter speed doesn't matter. You probably want to underexpose the "flash exposure" a bit, since you're just looking to brighten up the skin, not provide all the light for the subject.
You can start out with on camera flash in a fill flash setting, or manually dialed down to quite a low setting. You can diffuse the on camera flash with a bit of tissue loosely taped over it, or with a variety of home-made or purchased diffusers.
Moving on, you can use two lights, one on each side set at around 45 degrees, to start to get the classic "high key" look.
The hard part is balancing the flash and the natural light. Be gentle with the flash, otherwise you start to look like cheesy and fake.
ETA: Flash is just a tool, yelling at someone for not knowing how to use it isn't very productive or mature.