This paper contains brief introduction into modeling and simulation using Discrete Event Specified System (DEVS) formalism. It defines basic models (atomic and coupled DEVS) and shows how they are simulated. Examples of derived DEVS formalism like parallel DEVS or DESS are also presented. It is described how to create DEVS models using graphic modeling software and advantages and disadvantages of this approach. A short summary of known programs are also covered. Storing models in the XML language, validation of XML document and transformation capabilities by XSLT are discussed. The main section is dedicated to the design of a graphic editor for simulation models inspired by design patterns including classes for canvas, model representation, export module interface and main application. The XML document used for storing DEVS models and simple DEVS simulator are also described. Implementation section presents used programming libraries, reasons why they have been used and their advantages and disadvantages. Paper ends with an example of a simple DEVS model created by implemented graphic editor for simulation DEVS models.