I would set the SB-910 to Manual flash power control, not Commander mode; Commander mode would be for triggering OTHER, Nikon-protocol flash units using the SB-910 as...the "command-sending device".
I am assuming you want to use the on-camera SB-910 to trigger multiple, off-camera studio flash units, like monolights, or other studiuo flash units which have flash-sensing slave triggers, so, turn the optical slave control switch to ON, on the remote flash units, and then fire the camera with the SB-910 set to a lowish flash output level in MANUAL mode.
MANUAL flash mode on the SB-910 will eliminate ANY kind of pre-flash, so even the dumbest, lowest-tech optical slave triggers will reliably time up (synchronize) the shutter and the flash bursts. In TTL type flash control modes, the pre-flash unit the flash emits will NOT synchronize with "dumb" slaves, but only advances slaves which are specially designed so as to ignore pre-flash emission. Depending on the room/distance/position of the satellite flashes, as little as 1/64 power on the SB-910 might be enough power to trigger a remote flash unit. In some cases, you might need to go as high as 1/8 power.
You can aim the SB-910's flash head in multiple directions, to avoid it contributing much, if at all, the the lighting or exposure that is made by the satellite flash units. A tinfoil diverter, a cardboard diverter, or simply aiming the flash upward, or bouncing it off to one side of the room, all of those tricks can work to allow a low-power speedlight burst to trigger remote, satellite flash units operating on optical slave triggers. Once the MAIN monolight fires, its burst will easily trigger other satellite units: you only need to get light from the SB-910 to strike **one** powerful satellite flash's optical slave cell, and that one unit's output will in turn, trigger multiple others.