With the growing interest of Open Source Software Solution this paper proposes all the phases of software modeling cycle and processes towards the development of Functional Modules on 'Finance', 'Inventory', 'Purchase', 'Sales', 'Manufacturing', & 'Customized Apps for an "Open Source ERP Software" for the end-users (SMEs) guided by the Visual Studio .Net Studio & Framework in Windows application platform. This research combines the whole strategies for advancing towards such software modeling& development of a uniquely designed ERP Functional Module by encoding the required programming and the intensive study on the ERP Work flow and Business Logic on the other researches in this particular domain are performed to reframe the way of accomplishing the necessary objectives.