This is called a “High Key Portrait” because of the white background.

The toughest part of doing “High Key Portraits” is getting the lighting just right. Before I address that let me tell you why I like using them at times.  In this case the model wanted some head shots for acting career. It is easier to light her very evenly and let her move around and then capture “moments.”

Setting up for this type of lighting requires a few “know hows.”  First setup the background so it isn’t perpendicular to the camera.  A slight angle is needed. If you don’t do this you will have more photos with a flare. 

Place two strobes on either side slightly behind where the subject will be and angle them at 45 degrees to the background. 

Notice background and placement of the lights.

Place two strobes with shoot through umbrellas 45 degrees to the subject.  The closer they are to the subject, but not in the frame will create the softest lighting.

Meter the main strobes (umbrellas) and get them even in output of light. Choose an f/stop that give you the desired depth-of-field that you like.  Then set the background lights evenly and 1.5 to 2 stops greater.  Be sure they evenly light the background.

Take a few test shots.  If you look on your histogram and you have the blinking highlights function on, then the background should all blink and the subject should be fine.

I would suggest using a lens shade for this to cut down on the flare that is possible from all the lights.