Go to a running store and tell them you're looking for a shoe for the 'heavier runner'. DON'T go to a discount/chain store. They'll let you try various models, watch you walk, etc.... I did this; it was a close call between the Brooks Beast and some ASICS shoe. I'm 235 and went with the Beast.
Take it slow, walk a LOT and don't be dissuaded by people who say you're too heavy to jog. Oh, and if you can, run on dirt (trails in the park).
check out the following training schedule: I've been doing it for about a month now. No injuries yet.
http://www.coolrunning.com/engine/2/2_3/181.shtml
Best wishes,
Pat