This can be done using The Types and Tags tabs in your tools area.
There are some tutorials on this HERE.
I'd also like to recommend joining us for our Live, TheBrain 101 web event available every Tuesday and Friday at 10:00 am Pacific Time. This free web event is the best way to get started on your Brain. We cover all the basics so you will be able to get going on your own Brain quickly. We also take specific questions so you get a live demo of any aspect of TheBrain that interests you.