In Chinese, the family name comes first and the personal name second. As for pronunciation, it would be just as you spell it. Chinese spelling sometimes differs from our pronunciation, but in this case it would be Tran Quang as spelled.
Quang is the given name and Tran is the family name.
Although I get the feeling this question is a rather flippant one and perhaps someone's idea of a little joke.
Quite a harmless joke to be fair.
Got a problem Hangingbrain?
Thanks to the others. No, it isn't a set up 123. This man has put his name down for english lessons and I didn't know how I could welcome him into the class.
Which is the family name and which is the given name can be a problem even for other Chinese. Traditionally, the family name came first, but in places like Singapore and Hong Kong many Chinese have adopted the western custom of given name first, family name second.
To be polite, and get around any confusion, they'd address your man as ''Mr Tran'', just as, if your name were John Smith, they'll address you as ''Mr John''.
The only way to be sure is to actually ask the person!
I'm not sure how widespread that practice is in Hong Kong, my future wife is Hakkga (pronounced hatgar) and although she's lived most of her life far away on the mainland she has her surname first.
Also I have an ex who had the same practice, similarly I know many Hakkga and Hong Kong Cantonese (from numerous social groups) who use the surname first, but you are right it is easier just to ask.
They won't be offended, far from it, they'll be pleased that you showed the consideration to want to address them properly.