Please help me comprehend this sentence well.
"Once upon a time, in Smurf village, happy Smurfs were going about their happy lives completely unaware." Right now, I already know once upon a time is a phrase, it means there was a time but without an exact date. And "going about their happy lives", Is "going about" a high-frequency phrase which means lead or not? In addition, completely unaware is an adjective for happy lives? How could I understand this sentence from a viewpoint of sentence-composition?