Use the Column Layout button or Table Layout button in the Mashboard toolbar to change the number of columns (1-16) and/or rows (1-16) in column or table layouts. See Adding Columns or Rows and Increasing the Maximum Number of Columns or Rows for instructions.

See Set Size, Spanning and Padding in Column or Table Layouts for techniques to adjust column or cell sizes and spacing.

With columns, you can also add multiple apps or gadgets to a column. Table cells however only accept only one app or gadget.