Click on the WhatsApp icon. When it opens click on the telephone blue icon second from left, bottom row. Then click on top right telephone + sign. Your contacts that have WhatsApp should show . Select one and choose video or voice only. For regular contacts you can create a link to an individual or create a group, but that is mostly for texts and photos.
It may be an idea to text ahead that you are about to call, particularly if they are abroad.