I just noticed today that my dog can climb over the coral fence in my backyard(she used it like a stairway!).Does any one have any suggestions?

Fence problem

You can purchase wire and box to set up a small electric alternating current fence around you yard from Lowe's.
Another option is a radio collar for the dog that is activated by placing an underground wire on the perimeter of your property. As the dog approaches this perimeter, the collar will give it a small, harmless electric charge. This will train the dog to stay within the perimeter.