Insert ► Table/Matrix ► New...

New
opens a dialog for generating a table or matrix.

	Table	make a grid with no special options
	Matrix	make matrix rows/columns the width of the widest element
	Fill with	specify initial values for elements
	Fill diagonal	specify initial values for diagonal elements

Keyboard shortcuts: Shift+Ctrl+C (Windows); Shift+Cmd+C (Macintosh); Shift+Ctrl+C (X).