I can not for the life of me work out to take

Filming in a concert enviroment is extremely diffucult because of three major factors.

1. Lots of movement
2. Large distance between camera and subject
3. Uncontrollable lighting.

I would do this in full manual mode but you might just need a better camera as I'm not sure if you can do the following on your camera as I am not as familiar with this model.

I would set my ISO to the a very high count without it becoming grainy (1000+) and also would set my shutter to a relatively fast setting , say (1/500sec) and I would also use a tripod just to be safe. I would leave exposure at automatic , but would set my tone beforehand as the changing colored lights will probably mess that up.

That's about what you can do. Hope this helps.
Regards
Stephan