How to enable high speed flash sync with my Niko D3100 and my SB-700 speedlight?

I have a nikon D3100 and the SB-700, but i can't seem to get a faster shutter speed than 1/200, what can I do to get a higher shutter speed, please help me

The high speed flash has all to do with flash duration, NOT the shutter speed you use. More advanced cameras like the Nikon D300 and D3 have what is called advances Auto high-speed sync that can be used with specific Nikon dedicated flash units and sync at 1/320th second.

Your entry level camera does not have that feature.

Not all is lost.

Start with the ambient light low
Remember that the flash is stopping the action
Use a trigger to set off the flash
Set the flash to 1/2, 1/4 and 1/8th power to shorten the flash duration, opening the lens aperture to increase the exposure at lower outputs.

Here is how that works:

NOTE:

Digital cameras actually have very fast flash sync shutter speeds when compared to 35 mm film cameras. Some synced at shutter speeds of 1/60th or 1/125th second, so dSLR's have a slight edge over them when it comes to flash sync speeds.

You can't. 1/200th is the maximum on your camera for syncing with the flash.

It doesn't matter any way. The flash goes off faster than that.