Contact your county clerk by phone or visit their official website address. Ask him for an adult name change petition form, and ask what exactly needs to be done to make the name change effective.
Submit to a criminal history check, and go to court with your name change petition. The judge will ask you why you want to change your name--give her the truthful answer.
Change your name on important documents, such as your driver's license, social security card, credit and bank accounts and leasing agreements. You will need to submit proof of the name change, so get official copies of the judge's order before attempting to make any changes.