what a question. one that could take me hours to answer.
well if you are a begginner, then you should start on basic stuff (daa).
try doing simple vaults over small walls first.
a vault is a simple jump or hop over a wall useing your hands. as i said before, for more information visit
www.parkour.uk.org
these are often the hardest things for begginners to get over. its the feer of catching you feet on the wall that makes some people hesitate.
just relax, take a deep breath, and give it all you have.
stop thinking about the fact that you might be to fat to do this, or that you "not good enough", thats the classic excuse for not being able to do something. just do it, as our friends at nike would say.