Well it is a verse form consisting of 14 lines with a fixed rhyme scheme.
Step 1
Select the subject matter for your sonnet. Themes have often focused on love or philosophy, but modern sonnets can cover almost any topic.
Step 2
Divide the theme of your sonnet into two sections. In the first section you will present the situation or thought to the reader; in the second section you can present some sort of conclusion or climax.
Step 3
Compose your first section as three quatrains - that is, three stanzas of four lines each.
Step 4
Write the three quatrains with an a-b-a-b, c-d-c-d, e-f-e-f rhyme scheme, where each letter stands for a line of the sonnet and the last words of all lines with the same letter rhyme with each other. Most sonnets employ the meter of iambic pentameter (see Tips), as seen in these three quatrains from Shakespeare's 'Sonnet 30':
Step 5
When to the sessions of sweet silent thought (a)/ I summon up remembrance of things past, (b)/ I sigh the lack of many a thing I sought, (a)/ And with old woes new wail my dear time's waste: (b)/ Then can I drown an eye, unused to flow, (c)/ For precious friends hid in death's dateless night, (d)/ And weep afresh love's long since canceled woe, (c)/ And moan the expense of many a vanished sight: (d)/ Then can I grieve at grievances foregone, (e)/ And heavily from woe to woe tell o'er (f)/ The sad account of fore-bemoanéd moan, (e)/ Which I new pay as if not paid before. (f)
Step 6
Compose the last section as a couplet - two rhyming lines of poetry. This time, use a g-g rhyme scheme, where the last words of the two lines rhyme with each other. We refer once more to 'Sonnet 30':
Step 7
But if the while I think on thee, dear friend, (g)/ All losses are restored and sorrows end. (g)
Here is an example
First glance, I see your beautiful brown eyes.
I fall immediately under your spell.
Slipping into a dream, I hear love's sighs
The dream turns out to be a living Hell.
When you said you loved me, did you mean it?
Your lie is poisionous as blackened sin.
Your beauty cannot hide your soul, the pit.
Release the demon that has lain within.
I've looked into your eyes to find your soul
Wherever it has gone, I do not know.
Your mind controls the 'shell' it plays the role.
Your love is ice, as you know how to show.
Though you have proved the demon, played the role
I find all beauty in your broken soul.