The point is to read yourself whatever you like, not point
fingers. 
The last time I went, those who read just read one or two of their
poems. You can read poems, paragraphs from a favorite book (to be
considerate, maybe just avoid end book spoilers), or just any bits
of stuff you like. I think that time, Kenny said that if people
just want to read their favorite words is also ok. Don't have to be
very long. I think it's anywhere between 1-5 minutes.
It's more fun all around if everyone who goes just participate.
Don't worry about your voice, or what you are going to read, no one
is going there to judge you.
You don't have to have a loud voice, just read in your normal
talking voice, because the place is not very busy, so there's no
need to shout. 
