Hi rossim. The words to be placed in the grid are all part of larger phrases related to where the answers should be placed.
It may help to get the principle if you look at 24a which , if you have the answer you will note that it is "east of ????" , ???? being another answer on the grid. Similarly 57 across is "on ?????" ????? being another answer. 77a is "between two ........" etc
Hope this helps without either sounding like a bit of a smug swot or giving too much away......