How to fill the blocks of the Grid one by one?

[high_flyer]

I had made a grid of 16x16 on a widget,in which there are 256 blocks,
I also used a QPushButton with this.

What do you mean with "grid", a grid layout?
you mean you have 256 buttons in agrid layou on a widget?

If anybody understand my problem then Pls Help

You didn't explain what the problem is, only what you want to do.

If the problem is that you don't know how to do it then:
create a member variable to store the current block number.
Create a slot, and connected it to the clicked() signal of the button.
In the slot, fill the current block with color, and increment the block number.
Done.