Among all the other challenges you have in performing a respectable representation of another musician’s art, backing vocals may be foremost among them.  Even if you are a singer, odds are, you’re singing the lead part and may not know how to communicate the best harmony parts to the rest of your group.  It’s hard, learning harmony is at least 2 of the 8 semesters most music majors take toward their degrees.

You have a better way.

or rather Youtube is a better way.   Search for any song for which you wish an arrangement at the Youtube site and add “karaoke”  You’ll hear (maybe see) a version of the song without lead vocals but with backing vocals (if there are any on the original record).   It’s a great way to learn backing vocal parts.