You can pick any weekend or day that's good for you. You don't have to have ANY prior experience. And they give you everything you need, including transport down and back.
All they need is manpower, i.e. you. I can't tell you how good you will feel after doing this stuff. Please please PLEASE help out.
This is also a reminder that even donating $15 is helpful:
P.S. That I am able to easily post these links for you and get you involved in a campaign organized event is why I love the Obama campaign about 20 times more than the 2004 Kerry campaign.