form_for - resource-oriented style question

in my routes I have a route new_program_registration GET /programs/:program_id/ registrations/new(.:format) {:action=>"new", :controller=>"registrations"} to register a user in a training program

I preset the objects in the registrations_controller : @program , and

and have another route POST /programs/:program_id/registrations(.:format) {:action=>"create", :controller=>"registrations"} to receive the submitted form

I want to set up a form to get all data for this new user, but I know how to write the form_for helper in order to post the form to the create action of the registration controller I wrote :

<% form_for @user, :url => program_registrations_path(@program[:id]) do |form| %> <%... the all user textfields... ....

but it seems to be wrong...