If you want to join our
general discussion you can have a look, the first pages it has all the info you need.
Essentially it uses spare resources on your computers to run simulations on how proteins (building blocks of your body) fold. Stanford University is trying to understand why proteins fold to get a better understanding of why they misfold. This is looking into several diseases including Alzheimers and cancer. Most of the team run their rigs 24/7 for F@H.
Added: How - download the client from http://folding.stanford.edu/
Why - Each of us have our own reasons. Essential we are folding to help cure these diseases.