To move a cell or contiguous range of cells, select it and position your mouse over the selection outline. The mouse cursor will change to "move" pointer
. Now drag the selection by holding down the mouse button. Once you reach the target cell, release the button in order to paste the content.
Similarly, to copy a cell or range, hold down the CTRL key either before you start or as you drag the selection.
At any point of time while dragging, if you need to cancel the operation, just press the ESC key.