You will need
  • a good poem, pen, paper
To get started choose a poem that would fit for this case. Note that you can praise yourself, to compare with the great, and so is simply bad taste. The poem should describe some trait of your character, Outlook, attitude. The idea presented in the verses somewhat artsy (if the other participants do not intend to), but because success depends on the penetration and accuracy of a chosen poem.
If you do not find anything suitable - write the verses themselves. First define the idea of the work - what are you going to write, then intonation and rhythm (number of syllables and the location attributable to their accents). Choose the right meaning of the rhyme. Try to avoid imprecise and verbal rhyming, it always looks very unprofessional (example: got-tired shoes-oxfords).
Practice poems at home in front of the mirror. Read them out loud, the voice should sound somewhat louder than a normal conversation. Try to read expressively and clearly pronounce all sounds. You should not swallow words at the end of sentences, they must be heard clearly, but because of the long lines gain more air.
Most likely, you'll need a small speech, preparing the listener to the view in poetic form. This should be one, maximum two introductory phrase. For example, a short greeting and message about what you will now read the verses. If poetry is not at all clear describe/represent you should be included in pre-speech small sentence explaining the connection between you and the selected poem.
Speaking in front of an audience, be confident. To suppress the excitement, take a couple of deep breaths. Don't look at people's faces, look at the wall or over their heads (from the stage).