document.write should really only be used while the document is loading. Calling it after the document is loaded will clear the current document and write some new content. To add new content to the page, you would need to create new DOM objects and add them to the page or modify existing DOM objects.
Here's a small example of modifying the page you can see in action here: http://jsfiddle.net/jfriend00/zVS39/
HTML:
collections
Javascript:
function show() {
var o = document.getElementById("moreText");
o.innerHTML = "
collection 1
collection 2
etc...
";
}