Click on one of the buttons in the upper right and your computer will choose a root, 3rd or 5th.
In the boxes in the upper left, complete the major triad. Enter the root, 3rd and 5th from bottom to top. Carefully type upper case letters. Use # (shift-3) for sharps and b (lower case B) for flats. The computer will not recognize other lower case letters, spaces or other accidentals. Tab will move your cursor to the next box. Shift-Tab will move your cursor to the previous box.
Click the Check Triad button and your computer will determine if you are correct and tally your score.