I am writing Contextual Menu Plugins for Leopard OS and referring Writing Contextual Menu Plugins for OS X, part 1 article by Brent Simmons. My plugin is working fine.
Is there any way to move my test menu into main menu (above the Label)?
The short answer is "no".
The OS controls what gets displayed in that menu, so in order to change it around, you would need to call private methods, reimplement system-level functionality, and just in general do some Very Bad Things which would be unsafe, could break at a moment's notice, and possibly work differently between even dot releases of the same OS.