Disclosed is an apparatus and method to build programs from activity function units (AFUs) within a graphical environment. Each AFU is made from graphical representations of functional units (FUs). The resulting AFUs can be locked so that users cannot view proprietary and trade secret information as to how they accomplish their tasks. AFUs can be combined with other FUs and previously-created code represented in FU form to build large complex programs which are modified and added to by the user by means of manipulation of graphical elements on the computer screen without disclosing underlying coding.