i was reading this
http://www.skylit.com/javamethods/faqs/createjar.html

Creating a jar File in Command Prompt

  1. Start Command Prompt.
  2. Navigate to the folder that holds your class files:

     C:\>cd \mywork

  3. Set path to include JDK’s bin.  For example:

     C:\mywork> path c:\Program Files\Java\jdk1.5.0_09\bin;%path%  [color=blue][b]// done![/b][/color]

  4. Compile your class(es):

     C:\mywork> javac *.java [b][color=red]// has error message[/color][/b]

  5. Create a manifest file:

     C:\mywork> echo Main-Class: DanceStudio >manifest.txt

  6. Create a jar file:

     C:\mywork> jar cvfm DanceStudio.jar manifest.txt *.class

  7. Test your jar:

     C:\mywork> DanceStudio.jar

the error message is in the picture