The person's name that you want to talk to should come up at the top . At the top right hand side of the screen you will see a little square with a pencil. Touch there and search who you want to talk to. If you want to create a group, just touch Create New Group, and follow the instructions. the person you want to chat with obviously has to have WhatsApp too. It's a great way to communicate, I use it all the time. You can use it to make free phone calls too, as long as you have WiFi