How can you practice parts if you don't read music or don't have a piano?
It's fairly simple to do that for official Church hymns - if you know how. This page will teach you how!
Find the music you want on the Church's site.
In the box at the top, select Interactive Sheet Music.
Click on the volume slider button to open the volume selector.
Move all of the sliders to 0 except the part you are practicing.
You could also leave two parts on, or make all of them quieter except yours. It's up to you!
Then just click play and sing along.
You may need to adjust your device's volume up.
Before long, you'll have your part down pat!