Dark Skinned black girls are beautiful but I cant get the contrast in the photo right.?

Agree with keerok, increase the exposure so that their skin is +1 stop over indicated exposure.

Make sure that you're using a color-calibrated monitor.

You may even want to use an Color Checker Passport to ensure that the colors are spot on. Not exactly sure if sensors have a problem with Black skin, but color print film use to be incapable of producing accurate dark skin tones up until about the 1980s or 90s.

Of the ideas mentioned, the most important one is getting the exposure right. Common method of metering is to meter, then adjust the exposure so that dark or low-reflective elements (black cars) are dark, while highly reflective objects (e.g. white clouds) are bright. However, Black skin goes against common practice. You actually need to overexpose it by 1 stop which will allow you to get the best details and contrast.

Overexpose a little bit? +0.7, +1?

dark time in your life