Administration - Installation - Core: [ILIAS6.3] - Customizing Footer and TopNavBar

Hello,

we want to migrate ILIAS 5.4 to Version 6.3
For this i upgraded the Staging Environment. With the new Version i need to reconfigure the Customising again.
For this i created a new SKIN and reperforemd the Customizing with the ILIAS Systems (LESS).

Currently i have 2 Problem and hopefully you can help me.
I want to change the topnavbar logo. For this i copied the file tpl.main_menu.html from
/Services/MainMenu/templates/default to /Customizing/global/skin/myskin/Services/MainMenu
and changes the things i need to change. But the changes don´t get used by the system. 

The same for the Footer. I copied the file tpl.footer.html from 
/Services/UICore/templates/default to /Customizing/global/skin/BWV/Services/UICore
I changed the things i need to change, but the system don´t show the changes.

Is there a new File i need to copie and modify? The Readme was not really helpful for me :-)
Can someone help me please?

Thanks in advanced
Stefan