Here is my "go-to" reference:
RibbonX: Customizing the Office Ribbon by Robert Martin, Ken Puls, and Teresa Hennig
Although written for Office 2007, it is still gold.

You need to name your macro as a ribbon control.
i.e. Sub btnNewStyleSets_Click(control As IRibbonControl)

Take a look at my Continuous Page Numbering Add-In which has a single button added to the header tab with an associated macro.
For a different example where none of the macros are triggered directly by Ribbon buttons but rather are triggered through QAT buttons, see Random Text Add-In.