Go to their profile page and to the far right you will see a blue "follow" box. Click that. If you ever choose to unfollow just click" following" and you will then unfollow. To see the stream for your followed users just go to the streams, click the streams button and select "followed users".
Note. You can only sort the followed users stream by Hot and Latest. So you have to be willing to ignore their politics or whatever other content they post that you do not want to see. We are hoping they give us more sorting options later.