Simplify the following text for a Grade 8 native English-speaking person.
Original: Composed by Zubir Said in 1958 as a theme song for official functions of the City Council of Singapore , the song was selected in 1958 as the island 's anthem when it attained self-government .
Simplified: It was composed by Zubir Said in 1958 as a song to be sung at official events arranged by the City Council of Singapore .