Rocking it out

I purchased a good pair of green leather shoes. What I loved about the shoes are the metal dots embellished around them. When I wear them I get the feel of being a rocker chick but the thing is the elastic in the back part seemed to be in bad shape. The right shoe comes off my feet just when I start to walk. I really wanted to rock the shoes and I am all desperate to know how to repair leather shoes. Could somebody tell me?