3 lights, key camera right, fill, next to camera, one background left, pointed toward ceiling

They screw onto the 1/4-20 thread on the brass ferrule that comes as part of the umbrella bracket. The other ferrule that also comes as part of the umbrella bracket, has a 1/4-20 female thread that allows attachment to a light stand like a Bogen 3086. I got mine on ebay, but here they are:

http://www.bhphotovideo.com/... ...=productlist&A=details&Q=&sku=42516&is=REG

The background pictured is made using 107" wide muslin from Walmart, given a really bad dye-job by hap-hazradly dunking it into a RIT dye bath in the back yard. See below for how I did it.

I used umbrellas as light modifiers in my set-up.  The master SB-800 was attached to one umbrella stand and then the camera via a Nikon SC-28 TTL flash cord, to provide remote operation while maintaining i-TTL flash function. The other flashes were slaved via wireless SB-800 control.

Speedlights are, by nature, less powerfiul that studio strobes, and I was unsure, in my initial lighting research, as to whether speedlights would provide the quantity and quality of light that I thought I needed.   Light loss will occur whenever using any type of modifiers on the light source. Light will be lost anytime it is reflected from a surface, such as the white umbrella interior.  By diffusing the light (effectively un-concentrating it) additional light loss occurs as well. 

I expected 1 to 1-1/2 stops of loss due to the umbrella (at each light).  So I initially increased the flash compensation for each speedlight at each individual speedlight.  However, in practice, the light here, whether from three speedlights, or two, was very adequate to provide the level of illumination desired.   The only light I generally ended up compensating greater than one stop (or 0.0 EV) was the key light.

Key and fill @ +0.7 EV each, Fill @ 0.0 EV

What I learned (and maybe it is obvious to more experienced users) is that each individual light (key, fill, background, etc) can be compensated higher or lower than any other in the set-up. The relative intensities of the lights, with respect to each (lighting ratio), other can be set and maintained to provide ratios of 1:2, 1:3, etc.  For example, to get a ratio of 1:3, the key light (brighter one) should be set 1.0 EV higher than the fill.

The entire speedlight set-up can be compensated as a whole, up to +1.0 EV and down to -3.0 EV through the use of the flash compensation adjustment on the camera. (Push the lightning-bolt button and spin the thumb dial). Therefore, if the flash power is too little or too great, it can be compensated up or down within the range provided, while still maintaining the desired lighting ratio between key and fill

Here is a great site by Chuck Gardner that has a lot of information for additional reading on many topics, including lighting ratios:

I think I got the muslin at Walmart. It is 107 inches wide, and my original color for the one seen here was light blue. I bought 7 yards (21 feet @ 107 wide) for around $40.

The dying was quite easy as it needs to be a really bad job anyways to get the mottled effect.

You need a bottle of RIT dye, or equivalent, and a large tub, and rubber gloves. Follow the dye instructions---outside in the grass, it's messy. Wash the material in the washer to ensure it is wet. Gently wad-up the wet material, press it into the dye solution and let it sit for 3 or 4 minutes. Take it out, inspect, and touch-up by dipping some more. Let the excess dye run out of the material so it can be put into the washing machine on hot-wash, cold rinse--no soap. Dry in the dryer. That's it.

What you see is actually the product of a failed attempt plus a successful one.  My firsty try used a Denim blue color and resulted in a pretty uniformly blue color.  The second attempt used a bottle of Navy Blue and produced what you see in the shots.

See this website: