To the left of your title, you will see something like this ":="
Click that. Once you click it, a page will pop up. Inside the page, type this
If %SCORE > 100 THEN
BEGIN
$PAGETEXT := "You did very well."
END
IF %SCORE < 100 THEN
BEGIN
$PAGETEXT := "You did not do very well."
END
If you want to display the variable in the game text, then type this in your game text,
Your final score is %%SCORE%%