I sing a song

utau: sing
uta; song

Watashi-wa uta o utau.; I sing a song

Watashi-wa uta o utaimasu.; I sing a song.
With "masu" at the end, it is more polite.

Watashi-wa uta o utatta.; I sang a song.
Watashi-wa uta o utaudarou.; I will sing a song
Anata-wa uta o utau.; You sing a song.
Anata-wa uta o utatta.; You sang a song.
Kare-wa uta o utau.; He sings a song.
Kare-wa uta o utatta.; He sang a song.