What setting/mode on my Nikon D3000 should I use to take pics on halloween?

Well I just got my nikon d3000 and I'm taking pictures at school tomorrow. What setting/switch/mode should I put it in and which symbol is it?

I would go to "Scene" and choose either "Party/Indoor" or "Child". The child mode might work well since it softens skin tones and makes colors and clothing "pop" which would be good for costumes. Both settings also keep the flash on "auto" so you don't have to worry about that.

For lack of more details, set ISO to Auto, set to Auto mode and set flash to Auto.

http://www.illustratedphotography.com/basic-photography

I'm thinking "off" would be best, but plain old green box auto will work too.