My son just is potty trained. we started with the videos, and taking the potty chair in to the tv room. Then we put it into the bathroom and he started using it on his own. He used it about a week, then said he wanted to go on the big potty. He has always sat down, not stood for both 1&2. He was really scared to go #2 on the potty, so we just let him do the deed in the diaper. Faster than we thought, he just went on his own.
I would let your son be the guide; go get a video from the library and let him watch it, and stock up the bathroom with books. Make a chart; Ask every 15 min if he has to go. ..and nothing but positive praise!! It only makes things harder to push them.
I made a "road" chart with a car at the end, and told him when he went he got a sticker in each square. When the chart got filled, i took him to the dollar store to pick out a toy.
It worked so well, he was trained very soon.
Hope this helps. good luck, when they are ready -it seems to happen fast.