All creations are automatically "Public" once you create them. Letting your creations "Public" helps Google in indexing them and promoting your work!
However, if you want to make your creations "Private", it is very simple:
1) Go to "My creations"
2) Put the mouse cursor above the creation you want to be "Private".
3) Switch the button to "Private".
Please, keep in mind that only subscribers can put creations on private mode. All creations from free users are public. To see more benefits of a subscription click here or contact us: email@example.com