To visit neighbors, tap the Friend button on the left side of the game screen.
 

In the Friends tab you can view all your neighbors that you've already added.

   

The Explore tab is where you get random neighbors who you can visit and send gifts, even if they are not your Facebook friends. 

   

Next, select your neighbor’s profile then tap the Visit Farm button.

   

You can collect up to 5 visiting rewards from your neighbors daily!

   

To return to your farm, tap the Home button in the bottom left corner.
 
 
You can also send up to 5 gifts to your neighbors daily!