To follow another user, visit the person's profile page and click the blue 'Follow' button next to the username. Once you are following other users, you will be able to see questions they ask and answer under the My Q&A tab on the right, and then clicking the 'You Follow' tab on top. You can manage those you follow and can block others following you from the Connections tab on the left.
To see a current list of those you are following, and those people who are following you, visit your profile page and look for the two sections on the right sidebar.
If you have concerns about someone who is following you, please get in touch with Eric