[AndyField]

I think I've found the errors I've been making - I've now successfully been able to generate a .zip file using the following code:

// get the name for the saved .zip file
var filename = Dialogs.fileSave("Zip files(*.zip)|*.zip|", "zip");
if (filename) {

	// Generating .zip file
	// creates a new zip file to get a handle
  var handle = new Object;
	handle.value = 0;
	zipCreate(handle, filename, "");

	// grab a file from the resources panel
	var file1 = getAdditionalFile("example.swf");

	//	zipAddFile
	// adds files
	zipAddFile(handle.value, filename, file1);
	
	// closes and saves the zip file
  zipClose(handle.value); 
}

What I'm still stuck on is how to have an existing .zip file in the resources section and then add two additional files to it. Any ideas?