A JAR file is a file format that can be used to aggregate many files
into one.  Furthermore, a MANIFEST file can be used to specify the
path of the class that contains the main method to be used at startup
time.

Here, the file manifest.mf contains the following entry:

Main-Class: Run

Further information about JAR files can be found here:

http://java.sun.com/j2se/1.5.0/docs/guide/jar/jar.html

The command line option -m is used to specify the name of the manifest
when creating an archive:

jar -cvmf manifest.mf media.jar *.class *.java notes.txt

Be careful, if the option -m comes before the -f then the manifest
file must also come before the .jar file!

jar -cvfm media.jar manifest.mf *.class *.java notes.txt

Now, you can lauch the application as follows:

java -jar media.jar

or

double click onto the jar file!