Well if there are twelve forwards on a team and there are six teams, all you have to do is multiply twelve times six to get your answer of Seventy-two forwards.
The process is the same for finding the number of defensemen, except that you will multiplying six by six. This should give you the answer of thirty-six defensemen.
So your final answer should be: 36 defensemen and 72 forwards. Just incase you need it, that would be a total of 108 players altogether. Hope this helps!