How do you potty train a child that has autism?

My son is 42 now, but I still remember potty training him. I used a reward system. I had to make sure that he wanted the reward. For him, it was m & m s. First, he got an m & m for sitting on the potty for a short time, then longer and longer. Finally he peed when he was on the chair. Great cheers!! Lots of m & m s. Then the rewards got bigger and harder to get. For him, listening to a new record when he was successful. It took a long time and takes great patience. You have to start small: maybe just ten seconds on the potty. But it worked! I used the same system on my second son, who wasn't autistic, and it worked with him, too.