My 2 year old starting showing interest in the potty a few months ago, so we got her a potty chair and a book about potty training. We explained to her what the potty was for. At first, we would put her on the potty when she first woke up and at bath time, but didn't push her too much. Eventually, she started asking to sit on it, but she was very inconsistent. We didn't push the issue much, but I would give her a sticker to wear when she went potty. She loved the positive reinforcement, and would go just to get a sticker. When she was staying dry for long periods of time, we took her to the store and let her pick out her own underwear (she loved this!). We try and remind her to go about once and hour, and she is staying dry with very few accidents. She's even been dry in the mornings for over a week now.
Good luck! Potty training is difficult, and my personal theory is that you can't potty train a child who isn't interested.