Before attending a meditation retreat it is helpful to have a general understanding about meditation and the technique. The more you practice beforehand, the better. The purpose of practice is to cultivate the ability to focus single-pointedly with deep concentration, and the ability to surrender and remain in a state of non-resistance to whatever arises.
Here are some resources that you may find helpful, whether you are getting started in meditation, or you are interested in deepening your meditation practice. This series of guided meditations is focused on the breath. It is designed to cultivate the concentration and equanimity needed to realize Samadhi. The parts are not separate meditation techniques, but part of one evolving, continuously deepening practice of observing the breath.