I'm probably late getting on this, but when I potty trained my 3 children they were all around 2- 2 1/2. At your son's age, he should be old enough to understand the concept. I don't say this to be mean, but my nephew is autistic and he was around 6-7 when he was finally trained. Anyway, I found that the diapers and pull ups etc actually slow down the training. They are so good now that they pull all the "wetness" away from them and they aren't uncomfortable.
This will take about a week to do. (at least that's how long each of my kids took, not including night time, that took a little longer. What I did was to buy those cheap cotton underware. (Big boy pants!) All they wore was a t shirt and the underware (we stayed home for a week! lol!) This works well because it's summer. I gave them LOTS to drink. Everytime their cup was empty it got filled again. Keep the potty chair nearby. If it's been a while since they've gone, have them sit on the pot and "try". Don't yell or get upset if they have a "mistake" just clean it and them up and start over (buy a LOT of the cheap underware) When they do go on the potty (or toliet) praise them like crazy! (my sister used candy rewards, but I used just praise, it's up to you) When they have gone for a while without a mistake, try getting them "special" big boy underware, like spiderman or something like that. Tell them how it's "special" and you don't want them to go in their special underware. My daughters liked looking at books, so they had special books they could only "read" while going potty. (that helped real well for BM's)
Good luck and congrats on your progress so far!