Below, I discuss how to change the target class and give command line arguments.

You begin by looking at the project window. From there, click on the "Target Settings" button, as below:

From there, you choose the "Java Target" option, from which you may edit either the main class or the command line arguments. You should put the name of the class in Main Class text field. Make sure you do not include the ".class" extension or the ".java" extension. Command line arguments should be typed in the "Parameters" section.