Scirra website is very slow, the link does work, just try again.
If you are reading the questions from AJAX, you need to load them all into the array first:
Array set size to X=0, Y=1, Z=1
For x=0 to (tokencount(AJAX.LastData, "|")-1) : array Push trim(tokenat(AJAX.LastData, loopindex, "|"))
Then pick a random index from the array:
System -> set RandomIndex to int(random(array.width))
Then print the question:
function -> Call "show" (array.At(RandomIndex))
Then delete this index from the array:
Array -> Delete index=RandomIndex