Question: You allude to writing emotions in a story with "You'll know you have it right when the story flows in a way that is emotionally compelling." Please define and exemplify such success.Answer:
I simply meant that, in a well-told story, the reader becomes emotionally involved in the story and feels empathetic towards the characters and their dilemma, such that the reader wants to keep reading.
If your readers become bored by the story or feel no emotional involvement, they will simply put it down and move on to a different book.
Part of the secret to keeping the readers engaged is to have an escalation of emotional tension (anticipation, fear, hope, etc.). Tension should rise for the first three acts of the story. Problems become more complex, more difficult. The emotional tension peaks at the climax and then unravels in the final act when all is resolved.
Bear in mind, I'm speaking here of the reader's experience of the story, not the chronological order of events, since in some stories these are quite different.
For instance, the original question was about backstories. Telling a story in chronological order would mean that Chapter 1 would start with all the backstories, but that may not be the most emotionally compelling order. It may be more effective to keep the reader in suspense about a character's backstory until later in the book.
A small example...
In The Hunger Games
the relationship between Katniss and Peeta begins when she is starving and Peeta saves her life by giving her bread, even though he will be punished for doing so.
However, the book doesn't begin with this event. It begins on the day of the reaping, building up to the dramatic moment when Katniss volunteers to take her sister's place in the games. Then we have the relationship backstory in Chapter 3, after the reader has become curious to find out what will happen to Katniss, now that she has become a tribute.