Showing an image is simply SYSTEM create object (the box) and on this box place a Pinned text which will get a randomly generated number: int(random(1,36))
You will also need a GLOBAL variable to receive the same number for calculation purposes.
Then you need to know if the sum of the numbers picked by the player is adding up to your random number or not. For this also you can create a GLOBAL variable which will have a value of:
CONDITION 1) SUM of all boxes.
CONDITION 2) Box must be selected.
Then you need to compare the two with something like.
CONDITION) GLOBAL #2 = GLOBAL #1