Julie Andrews opens up about the high notes in her career as told in new memoir

The actress and singer sat down for an exclusive interview with Diane Sawyer.

Julie Andrews' beautiful voice, warm smile and joyful personality has carried her through Hollywood from her first iconic role in "Mary Poppins."

The English actress, singer and author sat down for an exclusive interview with Diane Sawyer and opened up about her golden years in Hollywood as told in her new memoir, "Home Work: A Memoir of My Hollywood Years."

At home, Andrews radiates with her smile and inviting warmth that evokes the same joy she has brought audiences for generations.

Fifty-six years ago Andrews, a stage actress at the time, boarded a flight to Hollywood, California, to make her very first movie -- and didn't have the first idea how to be a movie star.

Andrews told Sawyer she asked for directions on "how to say things" and what to do. She still remembers the first take for her iconic role as the magical nanny in "Mary Poppins."

"Dick Van Dyke said, 'You look very pretty today, Mary Poppins.' And all I had to do was walk across camera and say, 'Do you really think so?'" she recalled.

It wasn't how she said it, but the look on her face that told people there was someone named Mary Poppins who wanted to heal the world and make it right.

"She was very sure," Andrews said of her prim and proper character. "That's for sure."

From head to toe, Andrews brought Mary Poppins to life with the smallest details like that "the feet need to be turned out."

"I don't know [why], but you don't want droopy feet," she said showing her posing with her umbrella in hand. "They just sort of flapped about -- and I thought, 'If I just take off and try to walk as fast as I can, almost to be floating, it would make them have to run to keep up.'"

Early on, she showed she could do anything.

"I was very good at whistling," Andrews said, reenacting the skill that has certainly not been lost.

Every scene in the classic Disney film was a decathlon of sorts, filled with singing, tweeting and a huge contraption to make Mary Poppins float through thin air.

"There was a wire that went up my shoulder and down my back," she said, adding that someone else was "on the floor, actually, manipulating the robin."

Every scene had to be perfect and some even required six weeks of rehearsal. For instance, Dick Van Dyke, who played the chimney-sweep Bert, and Andrews had to balance atop anvils that later, through post-production, turned into turtles.

"And I was learning on my feet, Diane. I mean so fast," she said.

All the while, Andrews said she was up before dawn and home after dark to care for her new baby and breastfeed.

"P.L. Travers phoned me while I was in hospital -- the day after I gave birth," the actress recalled of the stern and formidable woman who created "Mary Poppins."

"And she said, 'Well, talk to me. I gather you're going to be doing Mary Poppins,'" Andrews said laughing. "And I said, 'Well -- I -- I've just had a baby and I'm feeling a bit groggy right now, Ms. Travers, but how lovely to talk to you.'"

Travers told Andrews, "'You're far too pretty of course, but you've got the nose for it.'" Andrews said she guessed that was about her "ski nose" that sloped upwards at the tip.

Andrews' husband, Tony Walton, was the costume designer and created a sort of secret message with Mary Poppins' wardrobe.

"It was a great help to me," she said. "He was -- well, is -- incredibly talented. And he said, 'I fancy that Mary Poppins has a secret life.' Kind of quiet pleasure at being a little wicked and naughty."

"Underneath all the skirts there were other colors. And so when I kicked up my heels or when I moved -- you just caught a flash," Andrews said.

Her new memoir shares more of her life story and explores the space where home and work collide. She writes about the courage it takes in a marriage with something that can't be fixed, summoning strength after a difficult surgery that took away her singing voice and singing a note that was designed to carry everyone closer to their happy ending.

Andrews' life began as a little girl who traveled endlessly through Vaudeville music halls around the United Kingdom while she helped support her unsteady, cracked family. Sawyer recalled that the actress grew up in a turbulent household of alcoholism, anger "and despair on my mum's part," Andrews added.

But as a child, her lonely life on the road still had some glimmers of hope.

"Four foot 10 and half. 79 pounds. Age 12. Experienced stage and radio," Andrews said, looking at an old photo of her singing for the king of England.

She promised her mother she would make it alright, and as a teenager, Andrews bought the family home.

Through it all, Andrews tapped into her supernatural talents to help escape from the sorrows in her life.

"I went to a C above high C in practice, but F above high C was twice nightly -- in my debut," she recalled of her high pitched notes that few others could hit let alone hold. "It was, like, four or five octaves, and I could, you know, dogs for miles around would howl when I went way, way up into the stratosphere."

She was taught to carry the note and hold them all "like a string of pearls, if possible." She said it was "just pure joy."

Her joy of that music propelled her through movie after movie with albums and concerts that shaped a golden career, but a struggle at home.

"I finally got enough courage after the first week to say, 'I don't understand why I'm weeping so much. I can't seem to stop,'" Andrews said. "You know, you're surrounded by the wagons. And suddenly the cavalry comes up over the hill in one of those westerns. And you weep for relief."

"Those lovely first movies were no help either," Andrews said laughing about her life, which had been geared toward a sort of perfectionism.

"Mary Poppins, practically perfect in every way -- and she wasn't. So there you are," she added with a laugh.

Andrews and her daughter Emma will share never before heard details about real life off screen with "Good Morning America" on Friday.

"Home Work: A Memoir of My Hollywood Years" will be available where books are sold Oct. 15.