That's all I want to say about that. You can arrange your page exactly the way you want it with some pretty easy code. But, they're not like spreadsheet tables or anything you might think a table might be. All other table codes and information should go between these two tags. You can put whatever number you want here.
Tables can consist of one to a gazillion rows.
Nesting means to put a table within another table. If you play around for a bit, you can swing some pretty nifty tables. Remember, if you're just trying to do layout, use Zero as your border and you can place stuff without showing a border.