This really is something that you will get different answers on. Simple things to start with are leaving the potty somewhere he can see it, kids of this age are curious, he will wonder what it is and what it is for. Tell him that it is HIS potty ownership will make him want it more. Also sticker charts work wonders or even a sticker book, non-food treats only. Something that worked with my daughter was when she had a bowel movement in her diaper was emptying the diaper into the potty and showing her that it went in the potty, messy and gross yes but she got the point and wanted to "put it in the potty herself" meaning she went in the potty, when she made that connection it got her to wet in the potty easier. Also try setting a "time to try" buzzer. They will not go every time but sitting there for a few moments when the timer goes off will inevitably lead to him going there once. when this happens praise praise praise! Don't push too hard though and never punish for accidents, he'll just start hiding it and the damage could last longer than any short term gains.