dude to get some cool looking shots, use the flash as well as a long shutter speed, meter for the background and find out how long of an exposure you need to take, and use the flash as well

this way your background in your photo will be properly exposed, the flash will allow you to "freeze" your subjects, but also, since you're using a longer exposure, there will be trails off the band members

depending on your camera and settings, the flash can either flash at the beginning (front curtain), end (rear curtain), or twice during the exposure