Repositories

You need at least 2 things:

• The project repository https://svn.atlassian.com/svn/public/contrib/confluence/updateable-sql-plugin
  For the project, you need both trunk (obviously) and the jar's directory where you can upload new release jars.
• The plugin metadata repository https://svn.atlassian.com/svn/public/contrib/repository/atlassian-plugin-repository/trunk/metadata.v2.confluence
  The plugin metadata is used to describe all the releases for a given project in terms of which versions of confluence they're compatible with and where they can be downloaded from, etc.

Make changes

Make changes to the plugin, run tests, etc. Using maven, this will produce a jar in the target directory (e.g. updateable-sql-plugin-0.0.6.jar). The version number is controlled within the pom.xml file.

Check in project changes into trunk. Check the jar into the jar directory. Verify that you can download it from https://svn.atlassian.com/svn/public/contrib/confluence/updateable-sql-plugin/jars/.

Prepare Metadata

Edit the edu.rit.se.updateablesql-metadata.xml file in the metadata repository. 

Basically, use previous releases as an example. For more info, you can start reading http://confluence.atlassian.com/display/DEVNET/Atlassian+Plugin+Repository+Details details on build number can be found at http://confluence.atlassian.com/display/DEVNET/Confluence+Build+Information though it might be incomplete for small update releases. Commit changes to this file, and the updated version should become visible in the confluence plugin repository.