2D Building grid

So I have done some tests googled around and found different examples about how to make a grid in mmf2.
I want to make a program where you can build stone blocks by holding the left mouse button and when you click save it saves the coords of the object into a array file.
And when you click load it loads up the array file. Now how can I make this program when you HOLD (not just single click) it creates 1 stone tile (32x32) that snaps onto the grid.
I hope someone got a example I tried a lot of things and extension.
Thanks for reading!