如果你会的话你可以跟在音乐后面唱.把这句话翻译为英语

If you know how to sing this song, please sing with the music.
If you can sing the song, sing with the music.

1)You can sing after the music if you can.
2)You can sing along with the music if possible/if you can.
还是第一个好些.....

you can follow the music if you can sing

You could sing following the music if you can.