I am looking to replicate nightclub portraits with sharp faces but blurry lights. Similar to the picture below:
I have read and been told to use rear curtain flash but after setting this on the Nikon D3000 it appears that my flash gun Nissin Speedlite fires as the shutter opens and when it closes not getting the effect that I desire!
Can anyone help me with tips on how to help this situation or any other tips for the best nightclub group portraits?

I have read and been told to use rear curtain flash but after setting this on the Nikon D3000 it appears that my flash gun Nissin Speedlite fires as the shutter opens and when it closes not getting the effect that I desire!
Can anyone help me with tips on how to help this situation or any other tips for the best nightclub group portraits?