Read the manual

or select "Modem Play help" from the Info menu

Summary help

1-make sure Setup is correct

  a-modem stings are correct
  b-matching modem speeds
  c-one and only one set for Originate
  d-if you are Originating make sure your opponents phone number is correct
  e-enter your name. It will be sent to the other computer/game

2-One player call the other
3-Agree on Setup
4-Hangup phones
5-Click on Connect button
6-If in Answer mode wait for ring
7-Game should start up within a few seconds
9-Have fun!!!

Press the E key to enter a message to send
- then press return to send

If you click to soon - press F5 (option-5) to get back to "Click to Connect"

If you are taking a long time to make your move press the Space Bar to let your opponent know  you are still there!