How to take a photo with my dslr where it blacks out the people?

I've been trying to figure out how to take a picture with my Nikon D90 (with 18-55mm lens) where it blacks out the people in my photo against a sunset, just like this photo below.

https://www.facebook.com/...b614e5eef8

photo credit: Cindy Brown

Make sure the flash is OFF.

Spot meter on the sky & drop it down a stop or so.

Foreground figures will then be several stops underexposed, ie a silhouette.

Example of mine;

You expose the shot for the background lighting and put the people in the foreground. With strong back-lighting, the people will become silhouettes.