This is the link of my patch:
https://gist.github.com/JiayanLiu27/8f8c8c726e2d1193116b41c677276e38
The first thing to do is to create another sequence follow the order of Oscillator(s) -> (Mixer ->) Filter(s) -> Level Control -> Effect(s). Then mix the two sequence together by an audio mixer and then put a stereo to let it sound out. After connecting all the modules, the next step is to modify the sound. I want to create an audio that is magic, enchanted and mysterious, something that can be used in the harry potter movie. I first try to adjust the tone color. I mute all the modules except the first Oscillator. The diagram on the top left corner is right for me. The diagram on the bottom sounds very electronic which I don’t want. 
Also the HPF filter makes the sound electronic no matter how I modify the rotary knob. And the comb filter makes the sound sounds like machine gun, which is not what I want, too. Finally I found that the classroom filter’s lowpass function fits my audio. Then I added a little delay to create the mysterious atmosphere.
The next step is to create the melody and the rhythm. I choose the 1/16 dotted for the main melody and the 1/8 dotted for the accompanying music. and the melody is not too low or too high with a certain flow.