How to communicate with the network table from the Dashboard

Curious how you communicate with the network table form the dashboard.

The WPILib documentation has a bunch of information on how to use the SmartDashboard, you can find it here:
http://wpilib.screenstepslive.com/s/3120/m/7932.

In a nutshell, any call to one of the SmartDashboard methods will put information in or retrieve information from NetworkTables. The SmartDashboard.put/get methods wrap this for you, so you don’t have to manually search for a NetworkTables key and find the value on your own. If you have any more questions, feel free to ask.

Thanks, but I’m trying to communicate from the smartdashboard extension, so SmartDashbord.get won’t work.

include the NetworkTables desktop .jar and use that.

You seem to be withholding information so I’ll have to guess what you mean. You mention extensions, so if you are writing a plugin, you call observable.setData(someDataSpecifierObject) where observable is gotten from the DataCore via getObservable(“some/path”) inside the registered() method.
However, I somehow doubt that is what you meant and instead are wondering about the UI. In that case, simply use a UI element that supports sending like the sliders or number box, then when running drag/edit them and the value is sent back.
If I guessed incorrectly and you mean something else please clarify what you are trying to do