I'm guessing you shot these in b&w mode Adele?
If so, and I don't know if this is possible on your camera, try turning the contrast down a bit. It will help the camera render more shades of grey between the absolute black and absolute whites in the image. As you learn to process your images you can add the contrast back in at a later stage......
Examples......
Low contrast settings in camera.......
and the histogram looks like this.......
you can see there are no ares of pure black (lhs) or white(rhs), all the tones are lumped into the middle (grey) so the image has no punch.
High contrast example.......
if you look at the histogram for this one........
you can see that the histogram is clipped at both ends, meaning there's areas of shadows and highlights with no detail at all, just pure black and white.
Yous should be aiming for something between the two.
Have a quick look around the web, there's loads of tutorials about this sort of stuff.