There are 2 options to customize ribbons in Nav Windows Client.

• Programmatically

For that set a value in page property PromotedActionCategoriesML. On msdn page How to: Define Promoted Action Categories Captions for the Ribbon you can find helpful informations. But … after many trials, i can say, it is not really working. In most cases tab “New” can be renamed, others not. Also adding new categories do not really work. Most of the ribbon settings are predefined by Microsoft and are not saved in the metadatas. They come like most captions from resource assembly Microsoft.Dynamics.Nav.Language.resources.dll. You can find it in <RTC base folder>/<lang code> (e.g. en-US).

• By configuration

It’s the best, better to say the only way, to manage ribbons, adding groups and/or tabs. For that best follow

• https://msdn.microsoft.com/en-us/library/hh879067(v=nav.90).aspx
• http://www.innovia.com/2015/10/28/customizing-profiles-in-nav-2015/

Ribbon groups can only be created by configuration. Configuring page ribbons for a group of users can only be done by running the windows client in configuration mode and presetting your admin user to the group’s profile.

For that follow

• https://msdn.microsoft.com/en-us/library/dn757305(v=nav.90).aspx
• https://msdn.microsoft.com/en-us/library/dd354992(v=nav.90).aspx

For creating a shortcut to nav in config mode follow
http://blog.encorebusiness.com/enable-configuration-mode-dynamics-nav-2013/

cheers