Fantasia Barrino and Oprah Winfrey Photo by: Bruce Glikas / FilmMagic

Fantasia Barrino has a big "thanks" for Oprah Winfrey.

Last year, the talk show queen cast her as lead in the Broadway musical, The Color Purple. Now, she's set to star in the new film version that Winfrey plans to produce.

The former American Idol winner got the good news two months ago.

"I was just coming out of surgery that day. I was drugged. As soon as I came out my manager came over to me and [said] 'Guess what? Good news. You got the part.' And I smiled. I couldn't talk. I smiled and I cried. That's the best news I ever got," said the 23-year old singer, who was in Washington on Sunday to perform at the D.C. Black Pride Unity party at the Avenue Nightclub.

She underwent surgery to remove two non-cancerous tumors in her throat. "I'm okay. We caught it at a good time," she says.

Winfrey, 54, also passed on words of wisdom to Barrino.

"Oprah gave me a lot of advice. She sat me down ... Just, you know, how a lady should carry herself. How to manage your money. How to not put your trust in everybody. Just watch your back," Barrino told PEOPLE.

"But most of all, you have to watch what you do. You have to carry yourself in such a way. You have to just watch your every move and carry yourself as a lady. So other young ladies who are watching you will know this is how you do it."

The fledgling movie star still watches Idol "faithfully," she said.

She wasn't surprised when David Cook was named winner of Season 7 on Thursday. "He's my favorite because he knows how to take songs and make them his own. I think he's ready for it. He has a glow about him. He deserves where he is right now."

So what advice does she have for Cook? "You just need good people around you and just be yourself."