Assuming you are using the D3200 in-camera editing features:
The Quick Retouch option will only allow you to edit and save the amount of auto saturation and contrast. It allows you to zoom to get a better view of a particular part of the picture, but you cannot save a crop from that option.
You need to use the Trim option that is near the top of the list just below D-Lighting and Red-Eye Correction.
- Use the +/- button to zoom in or out
- Rotate the command dial to cycle through different aspect ratios
- Use the four arrow keys on the multi selector to move the area of the crop around on the picture
- Use the OK button in the middle of the multi selector to save the crop as a new JPEG
It is all on page 152 of your Reference Manual.
With NEF (RAW) files, I would recommend you first use the NEF (RAW) processing option outlined on page 157 and then apply the crop to the new JPEG saved from that operation using the Trim menu option.