The default dashboard layout and applets can be found under:
Menu->Administrator; Default Dashboard
Please note that changes applied there affect only newly created users - it does not modify applets of existing users in any way.
The only way, as an administrator, to directly influence user dashboard is to go to
Menu->Administrator; Manage Users
Find desired user and click "Log in as user". Then - add/delete/rearrange applets.
There's no way to globally affect all users in the system, since each user manages his own dashboard and they may look very different from each other.
Kind regards,
Arek