NHL 11

easy. start your own HUT, then go to play now and go to the bottom where it says tournaments. at the time i could only enter the rookie one, but it doesnt matter which one you choose bc you'll still get the achievement

This is a fairly easy achievement to get, when you enter the Hockey Ultimate Team screen you are first given a starter deck, this includes enough players to start your team with a few spares.

To enter a single player tournament you need to go into Play Game in the HUT menu, then select Tournaments (Bottom Option). Using the trigger buttons change the tournament type to Single Player. You are eligible for the Rookie Tournament immediately. Enter the tournament, the game will warn you that once you start a tournament you cannot start another until you finish it. Select ok on that screen then select Play Match by pushing the A button. The achievement unlocked for me once I started my first game in the tournament. You are not required to win or even to finish the match however if you quit a game in HUT mode it is recorded as a loss and reduces the number of EA Pucks (currency) that you earn in future games. My advice is never to quit a match since you gain pucks for every game even if you lose so always try to ensure you have enough time to play a game before you start one. Good Luck!