My brittany spaniel smoke is scared of kids HELP!!!!!!!!!!!!!?

I want him to get used to the kids and I am ready for opinions NOT INSULTS!!!! although I wont treat train or click train, I use punish when wrong, praise when right, please answer without harsh words, he is not aggressive but he is so scared of youb spazzy people, I have bonded with this dog and I can't stand to see him scared, he is my best friend, and I just want him to be happy while still respectful THANKS!