First thing you should know is that EVEN UNDER WINDOWS, Java cares about file name capitalization. A class named Xyz has to be in a file named Xyz.java (NOT xyz.java), and compiles to Xyz.class.
Let's say I have a java file for package com.mousetech and the class it defines is named "Test". If I do a compile:
javac -d . Test.java
I'll see the following results in a directory tree view:
So I can run it by saying:
java -classpath . com.mousetech.Test
Note that "." means the current (working) directory, that to run the application you have to give its complete name (package name and all - peoperly capitalized!). and that you don't need to say ".class" at the end.