Find 10 schools your son would attend that are safe bets where you know he can play. The safe schools are your fallback schools. They should be schools that your son has a good shot of being successful at athletically and academically. The next 10 schools should be competitive schools. Then find 10 stretch schools (academically or athletically).

Then research the schools. Find out who is the recruiting guy at each of the schools. Put together a spreadsheet of phone numbers and email addresses. Then put together a package of info on your son with basic stats, measurables, achievements, and video. Send the package to all the recruiting coordinators. The email should come from your son, not you. Don't just send the same email to every school. Customize the email a little bit for each school and tell the coach/recruiting coordinator he wants to play ball for them.

As has been said above, you're late to the game. Ideally, you want to start the process during their sophomore year. The good news is that recruiting starts earliest with D1 schools, then filters down from there. Very small schools are still finishing up their recruiting of the 2019 class. D1 and D2 schools are currently focusing on the class of 2020. NAIA, JUCO, and D3 schools might still have room in their 2019 classes and probably haven't done a lot with the 2020 classes.