not able to run from command prompt

am using eclipse 3.2 for java development.programs are running from editor window, but whenever i am trying to run it from command prmpt , i am getting folowing error.............NoClassDefinitionFoundhow to resolve it...?
[250 byte] By [Yogesh.Turoc3a] at [2007-11-26 16:47:53]
# 1
DON'T POST AGAIN YOU FOOL, YOU ALREADY HAVE A SELECTION OF PERFECTLY GOOD ANSWERS. THE ORIGINAL ANSWER BEING "YOU ARE A LAZY FOOL".Ted.
ted_trippina at 2007-7-8 23:15:24 > top of Java-index,Java Essentials,Java Programming...
# 2
Cross-Post http://forum.java.sun.com/thread.jspa?threadID=5130862&tstart=0
masijade.a at 2007-7-8 23:15:24 > top of Java-index,Java Essentials,Java Programming...
# 3
Ted ......be cool....sometime it happens but dont loose control
Yogesh.Turoc3a at 2007-7-8 23:15:24 > top of Java-index,Java Essentials,Java Programming...