When specifying a form or container, you can also specify the layout. There are several layout managers. You can find more information about the use of them in the Developer guide:
http://www.codenameone.com/developer-guide.html from page 21.
X and Y coords are usually not used.
In a grid layout components are placed in the next 'free' row/column. Where it is placed depends on the order of components you place in the Grid Layout.