Accordion Click Event

Accordion Click Event

I have an accordion with a asp.net listview in the first header. I do not want to have the listview loaded when the page loads. I want to click the header and then run a function in my code behind that queries the database and binds the listview and then display the listview. I think the click event should be used or the changestart event. I just don't know how to achieve the result I want.