All content is stored in the workspaces in your network.  To modify access, there are several layers of security you can set for your users. 

For example, if you close access to a user at the Workspace Level, then you don't have to worry about setting permissions on any content in the workspace, since the workspace already denies access for the user.

Network level security is the broadest definition of membership in the network, and a user must pass through each layer in order to get access to any content.

These are the levels of security that a user must pass through to get to any content:

1. Network Level
2. Workspace Level
3. Folder Level
4. Page or File Level

As PBworks Admin, you have the ability to oversee all content inside all workspaces.  Click on each level to see more information about the level and how you can change and modify the settings of each level.