This assignment is for on camera flash, attached to the top of your camera. Ideally, the assignment is to turn your on camera flash backwards, if you have a flash that will turn backwards. By pointing the flash at a corner of a room you are making a big umbrella like light that will be soft and complimentary for a portrait. Also typically you will see less light fall off behind your subject, so your background won’t go as dark as a direct flash often produces. A small flash becomes a huge soft light source. Many flashes allow you to dial in the flash output to 1 over – 3 over or 1- under. If you aren’t getting the exposure you need, increase/decrease the output of your flash.
Also, put your camera on manual and vary your shutter speed to allow more or less ambient light in.
Pay attention to how the light is falling across the subject and adjust the angle of the flash accordingly so it looks good.
Play. Explore. It’s fast, it’s easy, you can immediately see the results and make changes. Notice how much variety you can get by varying where you point the flash, what shutter speed-iso-f stop you use.
At times, this approach will yield results that equal setting up lights on stands with softboxes or umbrellas. A great on camera flash is $300-400 new, and a lot less used. They are small, light weight, versatile and can do most of what a professional studio strobe head – power pack can do.