This is the name of the frame you want any linked page to appear in. If the applet remains blank when it is run off the server and never shows the image, the chances are there are problems with the image. If the image is too large then it may not be able to create the animation in memory. On the other hand, it may be that the image is not accessible. Again you will need to check the case and also the file permissions.
Some web browsers have trouble opening applets straight from a hard disk.
I have noticed this happen with Internet Explorer 3 and Netscape 4. This is an applet, it is intended for use within web pages. You can't open it directly. If you try, it won't harm your computer, but neither will it show you the applet. Class files are binary files, just like image files are.