There's nothing built in to Puzzle Script to facilitate scoring systems. Basically what you'll have to do is:
-- Define all the tiles you'll need to display scores (probably just sprites for numerals 0-9, if you want to display score as a number in base 10)
-- Write rules that increment the score
-- Have the actions in your game that are worth points trigger the score-increment rules.
For the middle part, I'd probably do something like:
1) define dummy objects and put them in the positions of the scoreboard: ones tens hundreds etc
2) define dummy objects that you can generate anywhere on the level when you need to indicate the score is changing: add1point add10points add100points and so on
3) have rules like this:
[add1point] [ones numeral0] -> [] [ones numeral1]
[add1point] [ones numeral1] -> [] [ones numeral2]
[add1point] [ones numeral2] -> [] [ones numeral3]
...