What are you trying to achieve?
If you're looking at editing the file directly, that is not recommended.
However, there are several ways to add objects, a few ways to edit objects, etc.
Could you describe what you are trying to do, what you've attempted, and what results you've gotten that are not what you expected?
This screencast, while focusing primarily on dynamic properties, also demonstrates some specific things you can do to update/add objects.
http://support.smartbear.com/screencasts/testcomplete/reliable-tests-for-dynamic-objects/
