beginner’s java applet question

I’m trying out some simple Java applets from a couple of books. I found that whereas I can always get them to run from Textpad or applet viewer, they don’t work in the browser, from an html doc. With applets that use the JApplet class, the browser doesn’t find the applet at all. I read somewhere that you sometimes have to use an older applet class (Applet rather than JApplet). I tried this too and now the applet displays but only some of the functionality works. Again, these are applets that run successfully from Textpad. Can someone point me to some solutions? I can post code if you like.