You cannot get an expunction because you do not qualify. You must have gotten a dismissal or a not guilty.
You may qualify to petition the court for nondisclosure if you served deferred adjudication probation. If the case was not reduced to a misdemeanor, then you will have to wait 5 years if the case qualifies, to file. If the case was reduced, then it depends on what type of case if there is a waiting period, IF the case qualifies.