Fill Light: is the source of illumination in your image that controls the lighting ratio or contrast in the image. The Fill Light will increase the exposure value of your shadows, decreasing the amount of contrast in the image.
How can you achieve this type of lighting? Since the goal of the Fill Light is to lighten shadows, you typically want to go with a large light source that will evenly cover your subject. NOTE: You don’t want the Fill Light to cast shadows on your subject. If it does then you will have conflicting shadows from the Main Light.
So, to make sure you get an even illumination, you can either use a Westcott 36x48 Softbox or another great choice would be to go with the Westcott 45" Round Halo. Since the Halo has a black backing with a silver lining, you are sure not to lose any light and with the curved front diffusion panel you are able to have a large soft light source.