Since Thin Image Upload is a Java Applet, your browser needs to have the java plug in installed. If the plug in is not available, the browser may prompt you to install it.
Just drag and drop your files onto the applet and they will be uploaded. This demo is configured to resize images if their height or width is greater than 400 pixels. It is also configured to accept only Jpegs and their total size should be less than 5MB.
Since only trusted applets can access local files please say yes when the security dialog appears