This is what you mean I am assuming. They are your obliques, and to be honest genetics plays a big role in how prominent they will be with each person.
In order for those to show you need to have very low bodyfat %, so start doing cardio or improve your nutrition. To develop them, you can do any of the exercises on the following page:
http://www.exrx.net/Lists/ExList/Wai...#anchor1944764