How to call one Form to another Form in Oracle APPS

DECLARE
   other_params                  VARCHAR2 (255);
BEGIN
   other_params :=
           'p_param1='
        || NAME_IN ('OKS_HEADER.id')
        || '&'
        || 'p_param2='
        || 'SC';
   fnd_function.EXECUTE (function_name      => 'CONTRACT_ESTIMATION'--Function Name
                       , open_flag          => 'Y'
                       , session_flag       => 'N'
                       , other_params       => other_params
                        );
END;