OK, so you've gone through your document and marked up all the block-level elements. But there's a few parts of your document left over that haven't been wrapped in any tags. Although you are certain these are block-level elements, you can't figure out what tags to apply.
What to do?
You may wish to consider using the generic block-level element: the division. This element does not have any specific connotations attached to it. But you may assign it meaning yourself. This makes it a potentially powerful element, especially when combined with style sheets.
A full exploration of the use of this element is beyond the scope of this introductory tutorial. Learn more about this element in the Using Style Sheets tutorial. The following example serves only to illustrate the basic syntax.
<DIV> ...content goes here... </DIV>
As you can see, this element follows the standard 'container' syntax, enclosing content between the <DIV> and </DIV> tags. But it doesn't have much meaning until you customize it.
The division is a block-level element.