YUI recommends YUI 3.
YUI 2 has been deprecated since 2011. This site acts as an archive for files and documentation.
This example will show how to open an "Image Browser" for the YUI Rich Text Editor.
Note: The "Image Browser" window will probably be blocked by your popup blocker.
Now, click on the "Insert Image" icon (the one outlined in blue) to see the "Image Browser" window.