rebranding

good day to all

i want to change the zimbra logo on the login screen and on the inbox. in which directory are the pages for these stored?

You can only rebrand the network version, and it includes a gui to change these assets in the admin console.

You can have a look at ZWC 5.0 Themes. But, as dave_kempe mentioned, there are certain rules to what you can do in the Community Edition vs. the Standard or Professional editions.