To copy the contents of a cell (or selected range):
Click on the cell whose contents you want to copy.
Point anywhere along the cell's border.
When the mouse pointer changes to an arrow, hold down the left mouse button and the Ctrl key.
Drag the cell outline, while keeping the Ctrl key depressed, to the target cell. Release the mouse button and Ctrl key.
The contents of the cell will be copied to the target cell. This has the same effect as copy and paste.
See also: