How to display error message on the screen

Question

I am new to WD world and need all possible steps to resolve the following issue.
I need to display the error message on the screen if any required field is empty when user click on SAVE button.
I have set the attribute GO_MESSAGE_MANAGER and check the both box for  PUBLIC and REFTO and set the associated type IF_WD_MESSAGE_MANAGER under COMPONENTCONTROLLER.
Under the method of COMPONENTCONTROLLER set the value WD_THIS-GV_NAV_FORBIDDEN = IV_NAV_FORBIDDEN. Which is type IMPORTING of associated type WDY_BOOLEAN.
GV_NAV_FORBIDDEN has been set to attribute WDY_BOOLEAN in the COMPONENTCONTROLLER.
Under the ACTION (on SAVE button) of my default view (VW_DEFAULT) I am doing the following.
IF lv_f_name IS INITIAL
    CALL FUNCTION 'BALW_BAPIRETURN_GET2'
      EXPORTING
        type   = 'E'
        cl     = 'HRRCF0002'
        number = '020'
      IMPORTING
        return = ls_return.
    lv_message = ls_return-message.
NEED TO PUT CODE TO PASS IT ON
ENDIF.

Answer 1

The thing I can not figure out is the input parameter of this call. My CONTEXT has a node1->node2->node3->f_name.
CALL METHOD lo_message_manager->report_attribute_error_message
  EXPORTING
    message_text              = lv_message
    element                   = HOW WIILL YOU FIND THE VALUE OF THIS
    attribute_name            =
   params                    =
   msg_user_data             =
   is_permanent              = ABAP_FALSE
   scope_permanent_msg       = CO_MSG_SCOPE_CTXT_ELEMENT
   msg_index                 =
   cancel_navigation         =
   is_validation_independent = ABAP_FALSE     .
wd_comp_controller->set_navigation_forbidden( iv_nav_forbidden = abap_true ).