my daughter is 20mths & we have been casually toilet training her for about 2mths. we moved to a new house & waited for her to be settled in & i introduced the "big girl undies". we went to the shop & she got to choose them & hold them until we paid. when we got home she was so excited & just wanted to hold them & play with them. it was funny to watch.
she wears her undies mostly outside, as there is no worry about the mess. when she does wees in her undies (always) i let her feel it for a few mins before i say "you've done wees in your undies. o oh. you should of done wees in the toilet" then i take her to the toilet & sit her on there, reminding her that's where she should of done wees. she gets changed & we get back to playing.
during the day i take her to the toilet to sit & she gets a stamp for sitting. she hasn't done anything on there yet, but as i said it's very casual at the moment, just getting her familiar with the toilet. she has a potty, but just plays with it mostly & i brought a little toilet seat, but she's happier to just sit on the normal toilet seat.
she runs away to hide when it's poo time... i don't pressure her to go on the toilet yet, as she gets very distressed when i ask her to do it on the toilet "no mum, don't want" & she runs away to do her business in piece. she then comes to tell me she's done a poo & we go to the toilet to change her. she sits on the toilet & gets her bum wiped, then we wash hands, etc.
i used to work in child care in the toddler room, so i have trained many children. some take to it like a duck to water, others are very reluctant to go near the toilet. you just have to be casual about it. introduce it slowly. don't put pressure on them./ except that accidents happen & don't make a fuss about it when they do. if your child decides one day that they don't want to go on the toilet, don't pressure tham, just accept it & wait until tomorrow. it will take a couple of months to get it all right!!!