If you want your table to have a specific width or height, be sure to enter it in this box. Width in Percent means a percentage of the width of the Web page as displayed on your browser. Border specifies how thick the outer frame of the table will be. Spacing specifies how thick the grid lines of the table cells will be. This kind of table can be used very effectively for page layout.
Different monitors have different pixel maximums.
An old monitor, for example, will not be able to display more than 640 pixels across and 480 pixels vertically. Some of this space will be used up by the browser itself. Tables should not be more than 550 pixels wide as a general rule. Add your content. When you are finished setting up your table, click 'OK' and fill the cells with your content by clicking on a cell and typing or pasting text or images.