Hello,
you have to first seriously start to learn a basics about how to use your camera and basic theory about the triangle Aperture - Shutter Speed - ISO + theirs "fifth element" (4th actually) which is Focal length
but basically, if you want to have blurred background you should shoot with longer focal lengths (but you have prime lens, you will be always shooting with 50mm on DX which is equivalent of 75mm on FX with your camera) and you should have your focus point close and you should use a big aperture (small number - just open your glass, use 1.8 - 2.8)
for everything on the photo sharp and in the focus, select smaller apertures (higher number, eg use 5.6 and above, sweetspot on your lens will probably be 8 or 9 which should suffice to most of the picture in focus) and focus on where you shoot or something like at 1/3 distance to your main object
to not have washed away the details in face (with light) you have to expose on the face .... this is the common problem when shooting outside and your dynamic range cannot fit everything .. it will be washing out skies and faces so you have to underexpose or use a bracketing (that's whole other story)
I suggest to quickly get familiar with basics so you have the idea what settings you want and shoot in A mode .. for to underexpose you can use +/- exposure correction button and dial which is on every (Nikon) camera .. I prefer this rather than using a manual mode - in past I was obsessed with using Manual mode but later I've switched to using in 99.8% A mode always with manual ISO and using a lot that +/- exposure correction tool