Simple Start

hi,
i am new to WordPress plugin development
can any body give me the code how can i add a top level menu
‘xyz’ at siteadmin and a single sub-menu ‘abc’ under it.

when i create a sub-menu inside the ‘xyz’ it creates 2 sub-menus. one with the same name as top-menu i.e. ‘xyz’ and the second one is the new one i am createing
i just want to add one sub-menu

plz help me with code

Faraz