If you mean you want to supply command line parameters to a WinForms app, then yes, you can.
All you need to do is:
string[] args = Environment.GetCommandLineArgs();
in you form code, and you will be given them.
When you register you app as handling a file extension, then a double click in Windows Explorer will pass the file path to your app via these arguments, for example - or you can add them to a shortcut on your desktop.
If that isn't what you want, then you need to specify rather better exactlky what you are trying to do, bearing in mind that we can't see your screen, access your HDD, or read your mind.