You may want to read this thread that was started a few weeks ago.
http://www.rottweiler.net/forums/pup...-15-weeks.html
It's not a good idea to be bringing puppy to the park to be playing with unknown dogs. A nasty dog may not like being bullied by your pup....and attack him...making him dog aggressive for life.
Get signed up for Puppy Kindergarten and keep on taking classes for the next couple of years...this is where you and he will learn.
Gina