You may decide to change a logo displayed at the top-left in CMS Desk and CMS Site manager.
1. Go to <your KenticoCMS directory>\App_Themes\Default\Images\CMSDesk for changing the logo in CMS Desk or to <your KenticoCMS directory>\App_Themes\Default\Images\CMSSiteManager for changing the logo in CMS Site Manager.
2. In either directory, you can find login.gif file. All you have to do is to replace this file with your logo image. Please note that your image file has to be named login.gif as well.