Use the username or email and password from your sign-up email.
Sign up to follow matches and get result alerts.
Create a league, invite your friends, predict match winners and exact scores, and climb the leaderboard. Lock your picks at least an hour before each match — once locked they're final, and you'll only see everyone else's picks for a match after you've locked yours.
Run a competition your own team plays in. Pick the format, invite teams, and let the bracket look after itself — results are checked against Dota's own match history.