To play chords press some of below keys on your keyboard (left hand):
A for a-moll
C for C-dur
D for d-moll
X for E (E key is used already for melody...)
F for F-dur
G for G-dur
To play melody press shown below keys on your (physical) keyboard.
(these keys have the same position as on a piano keyboard - look at the interactive keyboard below)
Red buttons highlight C sound on a keyboard.