How to make Jar files in JBuilder

I would like to know how to make jar files using JBulider. I have a problem with a project that I am working with in Swing. I have made the project on JBuilder and when I make a jar file it will not run upon clicking. Any body with an answer, please helpAbhi
[286 byte] By [abhimanyu31] at [2007-9-26 4:23:18]
# 1
It sounds like your Main-Class is not set properly in your manifest. To set your Main-Class, please follow these directions: http://java.sun.com/docs/books/tutorial/jar/basics/run.html
rSully at 2007-6-29 17:29:17 > top of Java-index,Desktop,Deploying...