If you are asking about the DNG converter, Yes you can and then the images will work in the older ACR version.
Look here for the list of supported cameras for version of ACR.
Just be sure CS5's ACR is updated to v6.7 and you set the DNG Converter for that. It's best to get the latest DNG Convertor. 9.8 for now. You'll be setting the DNG converter preferences to ACR 6.6 and later.
Adobe Digital Negative Converter 9.x gives links to that and instructions to set it up.
Lightroom 6? If you update it, it should work with those models without a converter. Not much of an expert there, so be sure to check the Lr forums for best advice.
I do not understand
if I go onto dng 9x it tells me that dng 6.7 is not for my camera & if I wont to go to 7.1 or above I require cs6 or cc .
therefor if it is possible to get cs5 to dng 9 or above with cs5 .please explain to some one who is not very computer savey
Since Camera Raw 6.7 (CS5) cannot read your Nikon Raw files directly, you must convert the NEFs to DNG.
Download and install the latest DNG converter which is 9.8
Open the Dng Converter, click on "Change Preferences" and set it to "6.6 or later"
Then place the Nikon Raws in a folder, select that folder, and click on Convert. The DNG files are created. Open those in ACR 6.7. For example double-click on the DNG file or open them in Bridge CS5.