Fewest guesses ranks first. Ties are broken by the time from opening the day’s game to the winning guess, measured on the server. A lost game is not ranked.
The daily leaderboard ranks solved games by the number of guesses. If players are tied, the quicker one ranks higher, using a time the server measures from the moment you open the day’s game to your winning guess. A game you lose is not ranked.
To post a result you need a display name, which you can set from the prompt after you win or later from the name control at the top right. For how to solve in fewer guesses, read the Daily Word tips, and see when the Daily Word changes.