What are the best settings for concert photography on Nikon D80?

Doing some concert photography tonight and first time with an slr at a concert… I have a AF-S DX 18-135 mm lens f3.5-5.6. I was wondering what i should set stuff too to get best quality. I will be shooting in low light conditions

Tis your lucky day. I have exactly same camera and kit lens. I would use shutter priority "S" and let aperture control itself as the lighting may change constantly. Shutter speed should be equal to or double focal lenght if camera is hand held. So if you use 135mm focal length use 125th/sec minimum. Don't use flash.
Next set ISO. Press menu button on camera > Shooting Menu > ISO Sensitivity > choose something between 1600 - HI 1. Realize the higher the ISO the grainier you photos will be and they will have lots of "Noise".
Next go to High ISO NR > and set to High.NR means Noise reduction. It will help clean up some fuzziness
Set Quality to Fine / Large to get best quality. You don't need to shoot RAW format. Then you need to tell camera to focus on wide or narrow area and to take exposure reading on wide or narrow areas. This is your choice and you will find both settings under "Custom Setting Menu" from main menu. Or use manual focus and manual exposure. The "P" setting will handle shutter and aperture automatically pretty good.