You can input chords using Chord button.
Click rightmost cell and set a red mark to the rightmost.
Click the Chord button to input chord.
Chord is input from the left.
The color of chord will be changed if you click the Chord box.
You can confirm the kind of the chord by difference of the color.
For example, C(black)[C], C(blue)[C7], C(red)[Cmaj7], Cm(black)[Cm], Cm(blue)[Cm7], Cm(red)[Cmmaj7].
If you have input a wrong chord, click Clear button.
You can change the chord using the red mark position.
Click the Compose button to compose a song.