I am completely lost. I understand that Lightroom 4 may not recognize raw files from my new D750. So I downloaded the dng converter and now I am unsure of what to do next?
You batch convert a whole folder of Nefs. Then import the DNG's into LR4.
Launch the DNG converter and choose your source folder.
Chose a destination folder for the DNG's
Click the import button and choose "Add" then navigate to the folder with the DNG files.
In the prefs section it's a good idea to choose "Fast Load Data" and then when you use the Develop module all the info is within the file without the
need to use the camera raw cache.
you need cr 8.7 or better and lr 5 is the minimum version that can update to cr 8.7.
so, as suggested above use the dng converter,