First of all, DO NOT assemble it on the light; one of those rods lets go and you're out a flash tube. Take the speed-ring off of the light and stretch out the fabric body of the SB into it's approximate shape. Take the flexible rods (4?) and insert one each into the rod pockets (little loops of material in the corners of the SB), and then place the speed-ring in the back, and force (and you may have to really FORCE) the rods into the holes in the speed-ring. That should stretch the body of the SB into the proper shape. Mount the speed-ring on the light and then install the inner baffle (if there is one) and the outer diffusion panel (usually with Velcro), and you're done.