You can use Table Styles to format the a table in your document, for example ...
If you have not completed the tutorial on adding tables to documents, click on the link below.
To change the formatting of your table, click anywhere inside of your table. Now click on the Design tab and find the Table Styles group.
You can click on any of the styles and your table will update itself. To get back to no style at all, select the first design option.
The selected formatting will be applied to your table automatically.