When you're creating the VI, you must select the inputs and outputs you want.
The result is the uploaded "find bounds of squares.vi".
In this case, it also requires some further modification to see what data you have. The order of elements in the "particle analysis" is in the order you request the data.
The modified VI is the uploaded "find bounds of squares 2.vi"
If you want to find the center of these squares, just average the left and right bounds, and the top and bottom bounds.