How to ajax

dear all,

I have a index.rhtml. And the preceding section of this page is a static
html. Such as



And the remain section is AJAX function call to a long time work.

I want the page show it’s preceding section (static html) first when
user surf it. And after AJAX call complete, it return the result and
display on the remain section.

How can I do it ? Thanks.

any tips is appreciated.