Instructions
Place your tetriminos as they fall in such a way that you end up with a hole in the form of a T-shaped tetromino. A T-shaped tetromino has a row of three squares with a single square below the middle square.
Fill in the rows surrounding your T-shaped hole so that filling that hole results in the completion of two lines.
Move any pieces that fall after you have prepared your move to the side to keep them out of the way. Wait for a T-shaped tetromino to start falling.
Press your left and right bumpers to adjust the piece so that it isn't angled correctly to fall into your prepared slot. Wait for the piece to settle into your slot and spin it at the last second to orient it correctly, completing the two lines and causing them to disappear. Completing this move correctly earns you the T-Spin achievement.