NoClassDefFoundError, I'm new

I compiled my first .java file and I made a .class file.....but when i try to run it from the prompt i get this NoClassDefFoundError.I saw in the FAQ that I should set CLASSPATH=, then try again, however I get the same problem.Anyone know what I should do?
[277 byte] By [Clendaroa] at [2007-10-2 0:06:11]
# 1

Change the cmd/command window to the directory that contains the class file.

Use this command to run it. Be sure to include the period and surrounding spaces.

java -classpath . name_of_the_class

If that works, then read about the classpath here

http://java.sun.com/j2se/1.4.2/docs/tooldocs/tools.html

The Installation Instructions for the Java package that you downloaded has detailled instructions on setting the path in paragraph #5. The same instructions apply to setting the classpath.

ChuckBinga at 2007-7-15 16:06:04 > top of Java-index,Developer Tools,Java Compiler...