Here's the rewritten pseudocode with the additional scores:
start
num myScores[12] = 78,95,84,92,88,85,94,89,97,82,99,87
num counter = 0
num highest = 0
while counter < 12
if myScores[counter] > highest then
highest = myScores[counter]
endif
counter = counter + 1
endwhile
output highest
stop