How do I read the tuner display to know if my string is in tune?

When the middle green light stays lit, the pitch of the string is close to the note name shown on the screen, indicating it is nearly in tune. When the left red lights stay on, the pitch is too low; when the right red lights stay on, the pitch is too high. Sharp notes are indicated by a small dot in the bottom right corner of the display. (Page 7)