Ribbon XML

You can display a custom tab when your add-in loads.
There are two different approaches that you can use:
1) Use the Ribbon Designer
2) Use an XML File

Images

More Details VBA > Ribbon > Images

Ribbon Designer

The Ribbon Designer is a Visual design canvas that lets you add custom tabs, groups and controls to both document level or application level solutions.

Ribbon XML File

If you need a more complicated Ribbon with finer control then you can use an XML file.

List of Control Ids

To help you find the ID of a particular control on any of the built-in tabs you can use the following references:
Office 2013: Control Identifiers - microsoft.com/en-us/download/details.aspx?id=36798
Office 2010: Control Identifiers - microsoft.com/en-us/download/details.aspx?id=6627
Office 2007: Control Identifiers - microsoft.com/en-us/download/details.aspx?id=3582