Your profile shows you the number of people you're following as well as the number of people following you. To see the list of people, tap on either Following or Followers.
You can also toggle between Following and Followers when you're looking at the lists by tapping their respective tabs.
You can also find more friends to follow from your profile page by tapping Find Friends.
You can find people by syncing your contacts and/or your Facebook account, or by search.
When you find someone, you can either tap on their name to view their profile, then tap on the top left to follow them, or just tap right away to follow them:
You'll see as confirmation. If the user's account is private, you'll see until they have approved your follow request.