Could not able to run the Mapreduce Example

Hi,

                  I tried to execute the example given in http://hadoop.apache.org/common/docs/r0.20.1/mapred_tutorial.html as explained in the tutorial. I was not able to execute the program as described in the tutorial. I am getting the error as shown below. I tried executing with some other examples. They are also showing the same “ClassNotFoundException”. I tried to find the solution in various websites but I could not find. Please help me to find the problem.
 

Exception in thread "main" java.lang.ClassNotFoundException: org.myorg.WordCount
        at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:247)
        at org.apache.hadoop.util.RunJar.main(RunJar.java:149)