As you have set primary chords as accompaniment to tunes by other composers, you should now attempt to compose your own melody with chords. Here is an example of an 8-bar melody which uses the primary chords.
Fig. 4
tonic(I)
subdominant(IV)
dominant(V)
I tonic(I)
Notice how the tonic chord in root position is varied. The quavers in the bass part create rhythmical interest in contrast to the melody.
tonic
dominant
tonic
tonic
subdominant
dominant
tonic
A leap of an octave in the bass on the dominant – E