Polyphony is a type of polyphony, based on the combination and simultaneous development of two or more independent melodies. In polyphony, in the process of its development, two styles were formed and developed: strict and free. Strict style or strict letter in polyphony. Strict style was improved in vocal and choral music of the XV-XVI centuries (although the polyphony itself, of course, originated much earlier).
How to make a tune? There are many different ways - from purely intuitive to quite conscious. For example, sometimes a melody is born in the process of improvisation, and sometimes the creation of a melody turns into an intellectual process. Try to encrypt the date of birth, the name of the girlfriend or mobile number in the melody.
If a person has a desire to compose a melody, then he, at least, is not indifferent to music and has a certain creative vein. The question is, how much "on you" is he with a musical diploma and does he have the ability to compose. As the saying goes, "no gods burn pots," and it is not necessary to be born Mozart to write your music.