I find your picture's to grey.
So with the pipet (image - adjustments- curves) you can choose a pipet.
You can select on the high, medium or low lights.
Standard it is on medium, I let that.
The left pipet is black, the middle is grey, the right is white.
If you click on the black pipet and choose the subject in the picture that should be black. Click and that part is black and make the whole picture a bit darker.
Then i did it with the white and click on the background. I find it to much so cancelled it and set it on high and made then the white curve.
Thanks Marc. I could notice a slight difference in your versions. Unfortunately I don't have Photoshop. Still working on trying to take decent pictures!