MachinaCraft is a framework for machines made up out of blocks, activated by right-clicking on a lever. On its own it does nothing, but other plugins can use it to let players build a Machina that they can activate.
General information about the plugin, comments page and issue tracker can be found at the BukkitDev project page.
You'll need some knowledge of how to create a bukkit plugin with Eclipse. If you're new to plugin writing, the Bukkit wiki has a tutorial that's a good starting point.
File -> Import... -> General -> Existing Projects into Workspace, select the MachinaCraft root folder. Repeat this process for each plugin folder contained in it. Eclipse should automatically compile each plugin when it's imported.
A rudimentary ant build system is included that can take care of packaging the plugins into jarfiles. In the MachinaCraft project, rightclick on build.xml and select Run As -> Ant Build (without the ...)
The jar files will appear in a 'jar' folder under the MachinaCraft root folder. Advanced: Create a new builder for the MachinaCraft project under properties so that you can just select the project and in the top menu choose Project -> Build Project.
When you've created a new java plugin project, right click your new project and choose Properties. Go to Java Build Path -> Projects tab, and add MachinaCore to the list.