If you just want four boards, just choose to print page one when the pint window opens. Once your bingo boards have been generated, go into the 'file' menu at the top left of the browser and choose print. If a set doesn't have enough vocabulary to make your boards, choose the 'blank option and fill in the remaining squares with text or have students draw in their own pictures in the blank squares.
2 boards will print on one sheet of paper for the 4x4 boards. 4 boards will print on one sheet of paper for the 3x3 boards.
You can make up to 16 bingo boards per sheet.