Arrays can store the values on the game board, so you could use a 2D array: dim board(6,20)
For actually drawing the playing pieces on screen, I would suggest using sprites. You could make each tetris shape a single sprite, or build the shapes out of single block sprites, which would require your code to position them into the correct shape. Once a sprite is created, it can be rotated and moved about the screen. Sprites are created from images, as you can see in the command syntax in the help.
( 2b || !2b ), that is the question. The answer: true