You must stay 300 ft from land and 150 ft from boats, people, etc while out on the lake. Otherwise you must be at headway speed. You all must be wearing a Coast Guard approved PFD. Make sure the one your son wears fits properly and will turn him right side up, and will not slip off.
You may need a NH boater's certificate to operate on NH waters, depending on the age of the driver. See the link for what year this applies to you.
You can take the course and get the certificate online.
Please look up and read the laws before you come and you will be ready for your fun.
Good Luck
Island Girl
How to tell if when you need a boating certificate