In read-only mode, click anywhere on a row to select it:

In single edit mode, clicking on a cell places that cell in edit mode:

In bulk edit mode, double clicking on a cell places that cell in edit mode. A single click on a cell selects the cell itself. Use the standard windows selection methods (left mouse click plus Ctrl and Shift keys) to select multiple groups of cells. A left mouse key drag operation can also be used to select multiple cells:

Right-clicking in bulk edit mode displays a pop-up menu with Fill Down, Fill Up, Copy and Paste options. Operations will apply to all currently selected cells