Hi sudhasrinivas,
I'm not an expert in
JSF - so I can only give you some basic advises to your code.
1. you need to submit each time the value in the dropdown changes - use "onchange" attribute in 'h:selectOneMenu' which referrer to a JavaScript function from where you submit.
2. use some kind of boolean 'flag' to control when the other dropdown(s) should be shown - when you submit, you enter your
java action bean, here you set a flag, and return to the same web page you came from
(I think that the attribute to use in 'h:selectOneMenu' is called 'rendered').