My camera won't auto focus?

I have a Nikon d5100 with a Nikon 50mm f/1.8D AF Nikkor Lens. I try to go to the info section where i'm told there's supposed to be a section sayin AF or AFS but there isn't. Do I have the wrong type of lens or am i doing something wrong?

IIRC the 50mm 1.8 DOES NOT have the AF-S motor, hence you've NO autofocus!

The Nikon 3*** & 5*** series NEED to have AF-S lenses (if you WANT Autofocus)

Your 5100 is like the 3100,3200,3300,5200,5300 in as much that NONE of them have built-in motors…
(hence the need for AF-S lenses "if" Autofocus is req'd)

I made sure right from the start that All mine had (future) AF-S lenses & 'V.R' capabilty
(you'd best to do the same in future too)

Your camera can't auto focus with an AF 50mm f/1.8D lens. Only AF-S lenses will auto focus on your camera.

Why? Because Nikon, as a cost-cutting measure to stay competitive in price, didn't put a focusing motor in your D5100. The more expensive AF-S lenses have a focusing motor in the lens to allow auto focus on your camera.

Had you read the Owner's Manual for your camera before buying a lens you would have know this and bought an AF-S 50mm f/1.8G lens.