Hello there, may I help you? I have a few ideas that may be able to help you, I have been working with young children for 17 years and have potty trained many times.
The important thing to remember is all children are different and are ready at different times to control their bladder and bowels.
It is important to introduce him gradually to the idea of training, explain what you are going to do but make it sound very special and exciting. Keep him in nappys but for an hour a day to begin with put him in pants and try using the potty about very 15 minutes, if nothing happens keep to this for a week or two, then increase to an hour in the morning and afternoon. Increase the time as the successes become more frequent or if he is asking to use the potty.
If nothing happened when he uses the potty simply say well done for trying. If he does do something make a big fuss, I used to do a wee wee dance which all my charges loved, we clapped and cheered and they had a big hug. Its about praise and building confidence.
Have a progress chart daily and every time he does a wee, let him choose a sticker to put on the chart, have a small reward for 1st wee, then 5, 10 and 20 wees, perhaps a new book or some bubbles nothing food related.
Take him shopping to choose some big boy pants too. Make it a special thing so he feels important and excited.
Here are some books to help him with the idea of using the potty. Available from Amazon Pirate Pete's Potty: A Ladybird potty training book [Board book] Andrea
Here is one that may help you too, also from Amazon Potty Training Boys, Dr
Caroline Fertleman (Author), Simone Cave.
I hope I have answered your question, please let me know if I can assist you further.