although you can find a lawyer to do the expungement for you, i think it it really not necessary. because major things you will have to do are,
contact local law enforcement to have your fingerpring taken.
file a motion to the court. ( actually a fill an application form for record expungement.)
present in a hearing if Distric attorney objects to your expungement, which is highly unlikely in your case.
pay the court fee for expungement.
then you are all set.