After selecting my image, I went to the edit, preference and then guides and grids option.   After doing this I chose view, show and grid.   After doing this I added a new layer and selected the rectangular marquee tool and drew m desired box.  I then filled the box with black.  After doing this, I held down my shift key and drew 10 horizontal rows and 11 columns.   I deleted the selected areas and added a drop shadow .  Then I opened my desired photograph. and copied and pasted it into my squares.  Then,  I created a clipping mask and moved the photograph in the best areas that suited the clusters.