For name change, you will have to follow the guidelines dictated and provided by your local state/county office. Please go to your local county Superior court and let them know about your decision to have the name change. In most cases you will be asked to pay a court fee, along with submitting your petition for name change. Also, publishing the name change in a local newspaper is required in most name change cases.
After your name change petition is granted, you will personally have to notify/update Social Security, DMV, passport etc.