It's actually not too hard! Press and hold the button on the lower left side of the face, until the display starts blinking. Then, use the same button to advance through the different time sequences (minutes, hours, date, etc.). Increase or decrease the values with the top and bottom buttons on the right side of the face. Then, when you're done - press and hold that lower left button for three seconds, and you're dialed!

You can download the full instruction manual here: http://www.nixonnow.com/manuals/newton-digital.pdf