There are several ways that you can search on Tag groupings - please click here to see a short video on how to use tag searching. 

Use the Tags search box and drop down menu in contacts, the other is by clicking on the tag cloud search icon as shown below in red:

How to search on Tags

1. Search within contacts via tag search cloud and tag filter box.

2. When you click on the tag search button a pop up window will appear with the tags that you have associated to contacts.  See example below:

3. Enter the name of the Tag in the Filter Tags box - see screenshot below:

Or Alternatively just click on a tag name to view the contacts in this tag group as shown below: