Everett,
The basic JAR exporting is provided by the base Eclipse (www.eclipse.org) IDE, not MyEclipse (J2EE addon to Eclipse). That being said, your MANIFEST file likely needs a line like:
Main-Class: com.whatever.dwd.Main
where you would put your full path to your Main class where I wrote com.whatever.blahblahbl. Then stick this in your META-INF dir inside of the JAR, or just make it part of your source tree, so when it gets zipped it is already there.
Then when people double click the JAR, and have Java fully installed, it will launch it.