Why follow?
You can follow users to keep up to date with what they're adding to their hearts. When you follow someone, all of their images appear on your Dashboard, so you can see at once what your friends are hearting.
You can visit other people's profile and if you like what they've hearted so far you can also follow them. It's ok to follow people you don't know, you'll make new friends.
Following
To start following someone, go to that user's heart and click on the "Follow" button next to the user's name. After you click you'll be following that person, and the button will become "Unfollow".
Unfollowing
To stop following someone (unfollow) you do the same thing as before, go to the user's heart and click the "Unfollow" button.