Born in Glasgow, Scotland in 1965, Kate Clanchy is the author of two prize-winning collections of poetry, Slattern (1995), which won the Forward poetry prize (best first collection) and a Somerset Maugham award, and Samarkand (1999), which was shortlisted for the Forward poetry prize (best poetry collection of the year) and won a Scottish Arts Council book award. Her latest collection is Newborn, a collection of poems covering pregnancy, birth and caring for a new baby.

In this exercise, you're going to write a letter to someone you have lost.

Any sort of "lost"- through death, distance, illness, accident or rage. Recently or years ago. A friend, a lover, a parent, a child. The first thing to do is to name the person and to think about him or her for a while. You might want to look at a letter or a photograph.

Now - some reading. This is all about tone. A letter is intimate, but also awkward and formal. It negotiates emotions within conventions, visceral memories and impulses within language. You are going to be doubly awkward and doubly formal because you are writing both intimately and publicly and in two forms: a letter and a poem. So you need some good examples of writers who can pull off this trick. Browning is where I'd start - "Two in the Campagna" or "Memorabilia". Evoking a sense of the person you are talking to is hard: for the right, piercing, almost embarrassing intimacy I'd turn to Americans: Robert Lowell, Sharon Olds or Donald Hall. Though of course, poets have been doing it for centuries: look at Hardy's 1912 Poems or Wyatt's "They Flee From Me, That Sometime Did Me Seek" or some of Shakespeare's sonnets. Finally, get hold of and play Famous Blue Raincoat by Leonard Cohen, or just hum it over to yourself. I prefer the original Cohen version on Songs of Love and Hate, but I know those who like the Joan Baez version. They point out that Joan can actually sing: I say that's the whole problem ... Either way, Famous Blue Raincoat, that sublimely cool and marvellously short monologue on love and loss will be our guide text here.

Stage one: Ideas

Start with some notes. Sit down with pen and paper and try responding to these prompts. Keep your pen moving over the paper rather than stopping to critique yourself.

1)

It's four in the morning, the end of December -
New York is cold but I like where I'm living ...
... There's music on Clinton Street right through the evening -

Your address. Where are you, now? Try to explain to the lost person. Be specific. What can you see and hear right now? What sort of room are you in? What sort of chair? What weather is it? What is the taste in your mouth? Don't try to state a mood, just stick to the concrete - as Cohen does here.

2)

I'm writing you now just to see if you're better ...

Introduce yourself. Why are you writing this letter - what's your occasion? Try to explain. It's fine to be awkward about it - look how well Cohen's awkwardness works.

3)

The last time we saw you looked so much older
Your famous blue raincoat was torn at the shoulder ...

How do you picture the person you are writing to? What is he wearing? Where has she come from? What is she about to do? What does he smell of? What is in her hands? Again, don't deliver judgements - stick to concrete details. Don't be afraid to use intimate language or cryptic details. Cohen never explains why the raincoat is "famous" - he just lets it speak volumes.

4)

I see you with the rose in your teeth,
One more thin gypsy thief -

Jot down another memory, this time showing another side to the person.

5)

I hear you're building your little house deep in the desert -
Living for nothing now, I hope you're keeping some kind of record -

What have you heard of the person since you lost them? Try some reported speech. What has it made you think?

6)

Did you ever go clear?

If you could ask this person one question, and have an answer, what would be?

7)

What can I tell you, my brother, my killer?
What can I possibly say -

You have one chance to tell this person what you really mean, what you really want. What is it? In plain language.

I guess that I miss you, I guess I forgive you ...

6)

Sincerely, L Cohen -

Now you have to sign off. Again, this does not have to be brilliant - you can work with the conventions of letter writing, as Cohen does. Sincerely, truly, with love ...

Stage two: Redrafting

Now you have to form your ideas into a poem. Two pieces of advice:

One: Try to be true to the poem rather than history. Tell a convincing story, not the truth. Remember, in life, Cohen's raincoat belonged to him, not to the romantic type he creates so well in the song.

Two: Be tough on yourself. Censor anything that sounds like whinging or self-aggrandisement. Give the other guy the great raincoat.

Stage three: Polishing

Actually, I think this the most personal bit of writing a poem. Other people's drafting processes aren't necessarily all that helpful at this point - so some very minimal advice: White space is especially important in this sort of poem because it represents the space between you and the lost person. Make sure your line-breaks and stanza-breaks are making full use of it.

Question all your adjectives and interrogate your intensifiers.

Watch out for hovering "ings": active verbs are often more effective.

Read the poem aloud a lot. Before you call the poem finished, turn it into prose and check your punctuation and that it all makes sense, then put the line-breaks back.

Loose the exercise: I hope to read poems from this workshop which bear no relation to Famous Blue Raincoat at all.

· Please submit your entry to books.editor@guardianunlimited.co.uk before midnight on Sunday 27 July