Answer by taking a quote from the following article:

Hedren was born on January 19, 1930, in New Ulm, Minnesota, to Bernard Carl and Dorothea Henrietta (nee Eckhardt) Hedren. For much of her career, Hedren's year of birth was reported as 1935. In 2004, however, she acknowledged that she was actually born in 1930 (which is consistent with the birth registration index at the Minnesota Historical Society). Her paternal grandparents were Swedish immigrants, while her maternal ancestry is German and Norwegian.

On October 13, 1961, she received a call from an agent who told her a producer was interested in working with her. When she was told it was Alfred Hitchcock who, while he was watching The Today Show, saw her in a commercial for a diet drink called Sego, she agreed to sign a seven-year contract. During their first meeting, the two talked about everything except the role he was considering her for. Hedren was convinced for several weeks it was for his television series, Alfred Hitchcock Presents. Hitchcock later said, "I was not primarily concerned with how she looked in person. Most important was her appearance on the screen, and I liked that immediately. She has a touch of that high-style, lady-like quality which was once well-represented in films by actresses like Irene Dunne, Grace Kelly, Claudette Colbert, and others but which is now quite rare."  Hitchcock put Hedren through an extensive color screen test that lasted two days and cost $25,000, doing scenes from his previous films, such as Rebecca, Notorious and To Catch a Thief with actor Martin Balsam. According to Balsam, Hedren was very nervous but studied every line, did every move she was asked to, and tried to do everything right. Hitchcock asked costume designer Edith Head to design clothes for Hedren's private life and he personally advised her about wine and food. He also insisted for publicity purposes that her name should be printed only in single quotes, 'Tippi'. The press mostly ignored this directive from the director, who felt that the single quotes added distinction and mystery to her name. Hitchcock was impressed with Hedren. As production designer Robert F. Boyle explained, "Hitch always liked women who behaved like well-bred ladies. Tippi generated that quality."  Afterward, Hedren was invited to lunch with Hitchcock, his wife, Alma, and Lew Wasserman, head of Universal, at one of Hitchcock's favorite restaurants, Chasen's. There she was presented with a golden pin of three birds in flight, adorned by three tiny seed pearls, and was asked by Hitchcock to play the leading role in his upcoming film The Birds. "I was so stunned. It never occurred to me that I would be given a leading role in a major motion picture. I had great big tears in my eyes", Hedren later recalled.

then what happened?
she agreed to sign a seven-year contract.