You can chat for free with users who are online and using the app. With others you can communicate via SMS/MMS in which case your carrier’s charges will apply
Open Messages Tab , all messages/conversations will appear below
Click on the icon in the lower right corner. Choose New message.
Enter the recipient to which you wish to send the message, you can enter more than one recipient
Type your message in the field and click on the send icon to send your message.
OR
Open Contacts tab
Click on the search icon
Type the name of contact you want to send the message to and tap on the contact
Click on the message icon
One check mark means sent, two check marks means delivered message