The ghazal (pronounced "guzzle"--thanks to Edward Byrne) is a Persian poetic form. The original form was very simple: three to 15 couplets using the same rhyme with the poet's name in the final couplet. The main themes were usually love or drinking wine.

Contemporary ghazals have abandoned the rhymes and insertion of the poet's name in the final couplet. In fact, even the themes of love and drinking wine are no longer mandatory--as the poem now just needs the couplets which are complete thoughts on their own but also all work together to explore a common theme (whatever that might be).

If you wish to stay traditional though, here's the rhyme scheme you would follow:
aa ba ca

and so on to the final stanza (depending upon how many you include).

Many traditional ghazals will also incorporate a refrain at the end of each couplet that could be one word or a phrase.

D.H. Lawrence wrote of the tendriled vine
of the juice and the climb and the entwining vine
wine

Visions, purple, melancholic or sweet, blood red, form in the grape
that clings, pulling juice, from the tendriled, groping vine.
Wine

drunk with visions, pulling, winding and unwinding flesh,
dreaming deep-supped, reaching Hohlwein. not whole wine, whole vine.
Drink