You got some requirements, you got some code, but those don't match.
Java is an object oriented language, so really you supposed to aim to write this program in an object oriented way.
You have mentioned dice, so that's a hint what tha class may read as.
Dice. Then you mentioned that such dice supposed to throw a number, well, maybe "roll" would be better.
So how about if you'd have such API?
Then in turn you could create more dices like that:
Then you easily could add dice.roll() part to a loop and roll as many times as you want, and in addition you could calculate sums that way.
Then you could create a mechanism to calculate how many times each of the sums appear. That way you'd have a bit more organized program instead of having everything in a Main class and main method.