1. Open Contacts
2. Click plus button to add a new contact
3. Tap in the first box - this will bring up the keyboard.
4. Note the order of entering names on your screen. You can choose later whether to have the names displayed by First name or Surname but for this to work the names must be entered in the correct field.
On your phone you may choose to have a different ring tone for individuals so that you can know who is calling without needing to look at the screen.