What wide angle lens I need for my Nikon

I have a Nikon D3100 which came with a 18-55 lens. I know very little about cameras, but I want to photo a person (about 6 foot) in a very confined space I can't get the camera far away back. I'm told I need a wide angle lens which will allow this. Will someone tell me the sort of lens I should buy.

Your 18-55mm is already a wide angle lens when you use it at the 18mm position. If it is not enough, then the Tokina 11-16mm f/2.8 DXII is my super-wide angle lens of choice. Make sure though that you buy the DX2 version as the DX version will not autofocus on your camera.

Other choices include the Nikon 10-24mm and the Sigma 8-16mm. All of these lenses will be wider than your 18-55mm.

You would need a fish eye lens.
so wide angle it makes everything curved.

http://imaging.nikon.com/.../19/01.htm

http://imaging.nikon.com/.../index.htm

http://imaging.nikon.com/.../index.htm

Yeah you will need an ultra-wide angle lens for that. You will either love or hate wide-angle lenses, I hated mine at first, but it grew on me. They tend to push things right back, so you have to stand really close to your subject. And landscapes get pushed right back too.

Your choices (least expensive to most expensive): Sigma 10-20 f/4 (120°), Sigma 10-20 f/3.5 (120°), Tamron 10-20 (120°), Tokina 11-16 f/2.8, Nikon 10-20 (120°). The Tokina is the best and sharpest with a very wide aperture. All those lenses can have screw in filters mounted.

The Sigma 8-16 f4 can't have screw in filters because its super wide with a bulbulous front glass element at 180°. It is extremely sharp if not the sharpest of all.

But who buys a lenses just to take a picture of a 6 foot talk dude?