I started walking for exercise and now I am having pain in the top right side of my right foot.It hurts to touch it and it is very painful to walk on it. Any ideas whay is going on?

It's likely to be a stress fracture, they are very common when you suddenly increase the amount of walking or running you do. Postmen are very prone to them.

Just rest it up as much as possible. You don't have to wrap it or anything, but try not to walk more than necessary until the pain is gone. It shouldn't take too long to mend. Fish oil and cal/mag supplements may help speed healing a little.