At the top right of your voucher, you will see the "SEND" button. After tapping on it, you will be presented with several options to send your voucher, either through your phone's messaging apps (including Mail, native SMS) or third-party apps that you have installed (e.g. WhatsApp).
You are now ready to send a unique URL as well as an editable message. Both the sender and receiver will need to have the latest version of the Yoyo app on their phone.
If the person you are sending the voucher to, does not yet have the Yoyo app on their phone, the link that you sent will take them to their app store. Once they have downloaded the Yoyo app, all they need to do is create an account (with just an email address and a password) and the voucher you sent will already be waiting in their voucher carousel.