Simplify the following text for a Grade 10 native English-speaking person.
Original: In the mid-1950s , Fitzgerald became the first African-American to perform at the Mocambo ( a Hollywood nightclub ) , after Marilyn Monroe had persuaded the owner to make the booking .
Simplified: In the mid-1950s , Fitzgerald became the first African-American to perform at the Mocambo , after Marilyn Monroe had lobbied the owner for the booking .