When you create a stream you can add the rule to display only contacts With or Without a specific tag
In order to do so you need to go into Create Stream => Contact => Contact Tag => With / Without the selected tag, select the tag in the list.
Once you have selected a tag from the list, click the orange button which says ADD RULE BELOW
Unless you want to add further rules, click the PREVIEW & SAVE button.
Give the stream a name, then SAVE STREAM & CONTINUE.
At this point, you may wish to add a trigger. If you prefer, you can do this later.