Expanding Background

I have seen what seems to be a common web site layout which will allow
for some type a graphic header and footer design with a bar or menu
joining the two along the left side of the page. As text is added to
the page exceeding the vertical limit of the page, the graphic along
the left of the page will automatically expand or tile to accommodate
all of the text and the header and footer will remain intact. The end
result would appear to be one image of a graphic header and footer
with some type of bar one or two or so pages long joining the two
along the left side of the page. I wish I could explain this better.
If it appears difficult to understand, I'll take another shot at it. I
think this particular format is used fairly frequently but I can't
seem to find any instruction to achieve it. Any help would be most
useful. Thanks in advance...

Fain