1) click "Ladder", and then "Join Competition".
2) go to http://dice.tripleawarclub.org/
and register the email you want to use for the ladder (you will a lot of email).
First round already started, but no worries!
You will be substitute for round 1 and get a opponent for round 2. If a second player sign in the next weeks, you will get him to play for round 1.
Have fun playing,