^ what twobob said.
There are so many things wrong with this file, I don't know where to even start...
First: the .azw2 file is not signed at all. Answer twobob's questions to find out out why this is so.
Second: the included META-INF/manifest.mf file should be called MANIFEST.MF (all CAPITAL letters). That's not a big deal, but still.
Third: your main class should be called "Main", not "main". Java doesn't really care about this, but you'll do yourself (and everyone else) a favor if you follow the commonly accepted
Java Naming Conventions.
Fourth: Your .class file is actually the SOURCE file, not the COMPILED bytecode!!!
All in all, I suggest you start with "an introduction to Java for beginners" first, before diving into Kindlet development. You seem to be lacking the very basics. Don't get this wrong, I'm not trying to offend you - I'm just stating the facts...