The Yoto Starter Pack comes with three blank cards that look like this:
These cards can be linked to any other cards or content in your library. You can also upload content via www.yotoplay.com/upload
To link content, use the Yoto app on your iOS or Android smartphone. Select the blank card icon in the card view and choose which card you wish to link it to.
Note: If you don't see a Yoto blank card in your mobile app your Yoto Player is running an older version of software. Yoto updates itself with new functionality automatically - but only when it's not in use - so all you need to do is leave your Yoto powered on and in about an hour the blank card will appear in your app.