HOW TO DO I CHANGE MY DAUGHTERS LAST NAME . HER BIOLOGICAL FATHER IS DECEASED SHE WOULD LIKE TO ADD STEP DAD LAST NAME

If the step dad legally adopts her, the court will issue an order which allows you change her name.   If he is not going to adopt her (for example if she is receiving Social Security benefits because of her biological dad's death) then you file the appropriate petition with the court.  This process includes publishing the name change notice in the local paper.  You can either contact your local courthouse start the paperwork or contact a lawyer to help you with the process.