First I assume you have placed all of your code into a single folder. You can have sub folders for your JavaDoc or your source files, I'm just assuming that we start at the top level of a folder.
Example folder named FirstFrame:

Example jar command:
The -cvfm are options:
- c specifies that a new archive should be created
- v specifies verbose mode
- f specifies that a file should be created
- m specifies what additional information should be added to the manifest
appJar.jar is the file name for the new archive. (The name can be anything but should have a .jar extention.)
main is the name of the text file with the manifest information. (The name can be anything but the file must be a plain text file.)
*.class and Test are the files/folders to include in the archive.
Note: If the fm options are listed in this order, the file name must precede the manifest option file name.
The manifiest option file includes the following:

This additional information specfies what class file contains the main() method that should start the program. When you enter this line make sure you press a carriage return at the end of the line!