The research aims to study how to add new components to Multisim database. Or how to model a component using the programing language C++ , to use this new component later in designing and making electronic circuits and devices. Multisim has built-in models for most types of devices, , the study aims to lay the foundations and method for modeling of electronic items which is not located within the Multisim program database, (or present with different values) , and that we need while using this program in the modeling and simulation process for a given circuit. Code modeling method has been proposed to reach this goal; this method relies on the behavior of the device or the modeled component. The study shows how to create a Code model for a specific capacitor that has different values to those existing within the database and add to it.