Tap the chef icon in the upper right corner of the screen to send and receive lives (W).
You can request and receive lives from the ‘Have a life!’ tab. Select ‘Ask’ to request a life from a friend (X). You can ask for a life from each friend once every 12 hours. Once a friend has sent you a life, tap ‘Get’ to receive it (Y).
Choose the ‘Give a life!’ tab to view requests from your friends. Select ‘Give’ to send a life (Z). Note that sending a life does not decrease your current number of lives.