He must do that for himself. It might take several exposures before your son will try a new food. Make no comment, whether he eats the new food or not. Once he does, serve it on a regular basis and go on to the next new food. Keeping a regular schedule for meals and snacks can also help.
New foods seem most attractive when a child is hungry, so avoid offering snacks close to mealtimes.
To further increase your son's interest in food, involve him in meal preparation. And, of course, don't forget to be a good role model. Although individual responses are not possible, questions of general interest will be answered in this newsletter. Parents trying to hook kids on good nutrition have several allies on the World Wide Web. Suitable for school-age children, teens and parents.