I have confrmed this issue with our developer, our WebCoverFlow will be loading image from the client side.

As demonstrated in this thread, our WebCoverFlow has the ability to load image from an external source.

.ItemsSource does not exit, I have .Items instead?

The tooltip says it accepts items of INamedObject2, but surely it's actually WebCoverFlowItem?

The thread I link earlier is for the WebCoverFlow in silverlight. Based on your description, it seems you are using the WebCoverFlow for ASP .NET. Here is the snippet in order to add a new item during page load event handler:

protected void Page_Load(object sender, EventArgs e)
{
    WebCoverFlowItem itm = new WebCoverFlowItem();
    itm.MediaType = WebCoverFlowMediaType.Image;
    itm.Source = "../images/iMovie.png";
    itm.Name = "cfItm1";
    itm.Title = "Test Item #1";

    WebCoverFlow1.Items.Add(itm);
}