Once you have gathered your course materials, you will have a better idea of what WWW tools you want to make use of. Don't worry if you aren't even sure what an applet is.
Some educators allow free use of their small programs.
Start by looking through the applets at The Educational Object Economy site. Look at examples of other courses in or not in your discipline for ideas. Remember that as with published materials, images and content on the internet are protected by Copyright Law. Perusing other sites is useful, but you generally can't copy images or content from other web sites. World Lecture Hall hosted by the University of Texas.