Want to buy a lens for my camera need some help just starting out?

Hi
just bought a nikon d3100 dslr camera, does normal af lens work ordo they have to be af-s lenses

Yah. But some of your camera feature would be reduced

You can use it but, you won't be able to auto focus. The auto focus for these lenses relies on Nikon cameras that have an auto focus motor built into the camera's body which your D3100 does not have.

If you want auto focus then you must buy AF-S lenses. The AF lenses will work just fine but you'll have to manually focus them.