How to make indie photos? Ones that look like this?

I really admire them and think they're beautiful. I have a nikon D3100 but I'm not sure if I'm supposed to get this effect in the camera or edit it later, or do I have to get an older camera?

You just need a fairly wide wide, fairly fast lens… Like a 30mm f1.8 or there abouts.
Use a wide aperture in the golden hour before dusk.