She has sung background for Barbra Streisand, Elton John and Bette Midler. She has written songs for Anne Murray, Roberta Flack and Earth, Wind & Fire. But now, at 29, Brenda Russell is taking care of her own business, without help from her former husband, composer Brian Russell (now married to Cheryl Ladd). Brenda’s second solo album includes eight of her pleasantly upbeat songs delivered with sassy-to-soothing vocals. There isn’t much to her lyrics, but there are some alluring melodies, particularly the glistening Rainbow.