Pretty straightforward. I recommend starting in Quick Play, as it can be your first win for the achievement related to winning 5 games in Quick Play.
Start your game and choose a second human player. The game allows multiplayer with one controller (Thanks Hasbro!). Once you start, play words until your player has the highest score. If you're first, just play as many tiles as possible.
Note the point total of your tiles. Add them together and subtract from your score. Make sure it will not result in a draw (both players with the same score or both at 0). If you are still in the lead after that quick math, continue on.
Have both players pass, twice. This will cause the round to end. Even if you don't "win", you still get the achievement for completing the match. If you do win, it's your first win towards the other achievement mentioned earlier.