Following your Facebook and Twitter friends allows you to keep up with what they're pinning and communicate with them right from Pinterest.
To follow your Facebook or Twitter friends on Pinterest, click your name at the top right of any Pinterest screen and select "Find Friends" from the dropdown.
Choose the social network you want to find friends from in the upper right.
If you haven't connected your accounts, click "Find Facebook friends" or "Find Twitter friends" and follow the steps to connect.
Click the "Follow" button below any friend to follow them, or click their name to see and follow individual boards.
Now, whenever you sign in to Pinterest, you'll see pins from that friend in your home feed.
Note that, depending on their settings, your friends may be notified when you follow them or their boards.