Alliteration is the repetition of consonant sounds at the beginning of each word such as Sally sold sea shells by the sea shore.
Consonance is similar but different. For instance, the repetition of two or more consonant sounds are within the word and neighboring words such as My mommy's hands were clammy. The repetition of the "mm's" within the words, not at the beginning of the words as with alliteration.
Assonance is a little different. This has to do with the repetiition of vowel sounds, such as You too are true. The repetition of the /ou/ or /oo/ sounds is present.
In terms of incorporating these into your poem, you'll have to see where you can change your wording around and blend some of these devices together without changing the meaning of your poem. Be patient when revising. Write your ideas down and then organize if needed.