Buy them a book
Honestly, I fell squarely in the camp you describe. I came from a background of SourceSafe and ClearCase. At first, GITGit was completely inscrutable to me, despite my boss walking through it several times.
What helped me was a book which clearly described what was going on, but more importantly, how GITGit was fundamentally different than any source control system that I had used before. Now, I prefer GITGit over any other choice.
Unfortunately, I cannot recall which book I had read at the time, but, just make sure whichever one you get for them (or point them at) focuses on how it's different and how it requires a different mind set.
Best guess for a book recommendation is:
Pro Git by Scott Chacon (Amazon link for ease... buy from whoever you want: https://www.amazon.com/dp/1484200772/ref=cm_sw_r_cp_dp_T1_BNruzbBQ8G9A6 )
NOTENote: Do NOTnot buy a reference book for GITGit. That will not help at all.