If you do not have the source code for a particular application and you are interested in seeing how it works, you can use .NET Reflector.

To debug an executable:

1. Open your project in Visual Studio.
2. On the .NET Reflector menu, click Debug an Executable.
3. Select the executable you want to debug and open.
4. On the .NET Reflector menu, click Choose Assemblies to Debug.
   The Debug and Decompile dialog box is displayed.

You can now follow the steps outlined in Decompiling assemblies.

Setting command line aguments

If you require particular command line arguments to be set when running your executable, you need to create a "dummy" project in Visual Studio. The original executable can then be run with the command line arguments:

1. On the Project menu, click [Project name] Properties, and then click the Debug tab.
2. In Start external program, type the executable name.
3. In Command line arguments, type the arguments used by your executable.

You can now start debugging in Visual Studio.