Inserting Empty Row into Web Dynpro Table

For example with a node called "Details" which is bound to your table. A new line is added at the top of the table.

data: lo_nd_details type ref to if_wd_context_node,
        ls_details type wd_this->element_details,
        lo_new_element type ref to if_wd_context_element.

  lo_nd_details = wd_context->get_child_node( name = wd_this->wdctx_details ).

* append a line to the node
  lo_new_element =  lo_nd_details->bind_structure( new_item = ls_details
                                  set_initial_elements = abap_false
                                  index = 1 ).

I would strongly suggest that you read/view some of the excellent eLearnings that Thomas Jung has put out - they give a good introduction into basic WDA coding such as the above.