If you mean you know how to add a new tab using Customize Ribbon in options then that is NOT the way to go if you need to add your own code or userforms.
The free App CustomUI Editor allows you to design new ribbon tabs and menus but you will need to learn some XML and then vba to make the buttons work.
There is a very trivial tutorial on our site (with a link to the App)
http://www.pptalchemy.co.uk/custom_UI.html
There is also a free kit on the page with Ribbon XML for 4 macros done ready for you add your own vba.