Good for you for asking for help, that's the best way to learn!
Here's my advice, I hope it's not too jumbled:
I'll start with the lighting of the location: You've got subjects standing with the light behind them. See how the light is showing through the boy's hair and on the man's shirt? The light is coming from behind. Since you were using your camera on auto, the light for the entire scene was averaged to come up with the level of brightness you ended up with in your photo (too dark for your subjects). To perfect this exposure, you needed to meter off your subject's face - this means instead of letting your camera come up with its settings by reading the average amount of light in the entire scene, you need to get it to read the amount of light that's falling on your subject's skin (or on something else that has the same amount of light falling on it, for example the rocks on the ground in this picture). This stops the high contrast between the subjects and the background from causing problems. Do you know how to read your camera's meter? I'd recommend the book "Understanding Exposure" by Bryan Peterson as excellent reading to get you started.
If you wanted to stay on auto, then you'll get better pictures in situations with lower contrast - E.g. angling the camera down so the photo didn't include the sky, or positioning yourself on the other side of them so the light would hit their faces rather than their backs.
Definitely start playing around with settings and see what you can come up with. And ask any questions you have!