After launching Bytessence AMVConverter, click on File and select Add video, then browse to the target file and load it into the application. Next, click on the task which appears in the main window and press the Start button (the one that looks like a sun)
In case you run into any issues or you have additional questions I recommend consulting the help section and if the answers aren't there, you might want to use this email address: support@bytessence.com to contact the developers directly.