Set the width and height of the table by applying CSS to the containing div. Eg:
style="width: 100px; height: 100px;"
The width and / or height can also be set to a percentage. Eg:
style="width: 100%; height: 100%;"
If using % for your height, then make sure the container you are putting the grid into also has height specified, as the browser will fit the div according to a percentage of the parents height, and if the parent has no height, then this % will always be zero. If your grid is not using all the space you think it should, then put a border on the grid's div and see if that's the size you want (the grid will fill this div). If it is not the size you want, then you have a CSS layout issue to solve outside of the grid.
If the width and / or height change after the grid is initialised, the grid will automatically resize to fill the new area.