Complex sentence: Cyrus promoted the song by performing it in several venues, including during the opening act for the Cheetah Girls'The Party's Just Begun Tour and as the closing number on her own first headlining concert tour of the same name.
Split into simpler sentences: Cyrus promoted the song by performing it in several venues. This includes as the opening act for the Cheetah Girls in The Party's Just Begun Tour and as the closing number on her first headlining concert tour of the same name.