Use the quick add feature at the bottom of the contact manager table to add a contact to an existing or new group.
As a minimum requirement the contact must include a first name and a phone number (in international format) and a contact group. 

You can also add email and Surname. 

Once the requirement is met you'll notice the  "Add"  button turn green. 


Click on the green Add button and you should see a pop up message at the bottom of the screen confirming that the contact is saved.