Problem with background images_html/css_WEB-ITnose

The background of the website is a whole big picture. If there is more content on the web page, the whole big picture will be repeated. Now the big picture is divided into three sections, header, footer and the middle part. Now I want the header to always be at the top. The middle part is In this part, if the page has a lot of content, repeat-y, and the footer will always be at the bottom.
Dear gods, please help.

Reply to the discussion (solution)

Now divide the big picture into three sections header footer and the middle part
re:
These three sections are still in one picture inside?

background:transparent url(xxx.png) no-repeat scroll ?% ?%;

?% ?% Define header, footer, and middle height

Now divide the big picture into three sections header footer and middle part
re :
Are these three paragraphs still in one picture?

background:transparent url(xxx.png) no-repeat scroll ?% ?%;

?% ?% defines the height of header, footer and middle

It has been cut into 3 pictures

#header{...} #body{background:url(footer.png)repeat-y center center}#footer{background:url(footer.png)no-repeat center center}

#header{...} #body{background:url(footer.png)repeat-y center center}#footer{background:url(footer.png)no-repeat center center}

Thank you, I will give it a try. Dare I ask the master how much QQ is?

#header{position:fixed top;}
#body{background-image :url(),background-repeat:repeat-y;}
#footer{position:fexed bottom;}