Saving and loading objects under bluemud is straight-forward. If you've built a class (such as a bulletin board) and it's your intention that instances of that class should be saved to disk and later reloaded, you need to do three things: override the save method, override the load method, and add the stdprops.IS_PERSISTENT property to the instances you want saved.
The save method should return a map of the instance attributes that you want to save. Each key should be a string representing the name of an attribute and each value should be the value of the attribute. When the object is reloaded, the load method will be invoked and passed a copy of the map that was returned by its save method. It's the responsibility of your implementation of the load method to set the appropriate attributes on the object instance from the data in the map.
Object saving and loading is actually initiated via the mudlib.stdlib.saveObject and mudlib.stdlib.loadObject methods. The saveObject method should be passed the object instance to be saved and the name of the file to which it should be saved. The saveObject method will take care of invoking the save method on the object instance and requesting that an object image to written to disk.
The loadObject method should be passed the name of the file where an object instance was previously saved. It will take care of constructing a new instance of the object and invoking its load method, passing it a copy of the map returned by an earlier invocation of the save method.
For more information, see the documentation for the mudlib.stdlib.saveObject, mudlib.stdlib.loadObject, mudlib.core.Object.save, and mudlib.core.Object.load methods.