Please don't take him to the dog park unless he is updated with all of his vaccines. Malinois are A LOT A LOT of dog like I said. How is his energy? If he infact does have Malinois in him, you need to put him in some kind of sport like Schutzhund or something. He needs to be worked with a lot. I know he is just a pup, but pups can do Schutzhund which is basically for personal protection. I would look into clubs in your area. :)
http://en.wikipedia.org/wiki/Schutzhund
There is a forum I can recommend to you if you want, a lot of Malinois owners there and they can give you some advice how to work him and that. :)