Best Recumbent Bike

I am a 66 year old breast cancer survivor. I have gained 90 pounds since my treatment a few years ago. My question is, I would like to walk in the 5 mile Komen for the cure walk next may. I am getting a new treadmill, and have a recumbent exercise bike. I am retired, so have all the time in the world to get into shape. I need a healthy diet and exercise routine to follow everyday. If there is a fitness trainer or someone in the know, I sure would appreciate your help. Thanks