I was anxious when I was first involved in potty training. I'd heard so much about how difficult it could be and if not done "right" could damage the child's self esteem, etc. I've found that potty training, tho it does require attentiveness and consistency, is not difficult if the child is ready.
One of my friends put off potty training until her daughter had to be trained to be in preschool. She learned in 1 week. The mother put a potty chair in the bathroom and she and her daughter talked about the process. At first the little girl just liked to sit on it but when she saw her mother using the big toilet she got the idea and had fun running to her potty, even when she didn't need it, during the day. Her mother's positive attitude and lack of pressure helped this process a lot. I think she also used stickers as a reward.
Both of my grandchildren took several weeks to learn but then I was babysitting them and I wasn't consistent. When their mother took over and when my grandson went to a small daycare it was done in a couple of weeks.
When we say babies have to be ready we mean that their sphincter muscles must be developed enough to hold back urine and poop. Being ready also means that they are emotionally wanting to learn. The reason that they take longer to learn to poop in the toilet is that those sphincter muscles develop later.
It is quite possible that a 2 1/2 year old girl is not physically ready to use the potty. But you could get started by reading a child's book about learning to use the potty with her and putting the potty seat in the room in which she plays so that she will start to get used to the idea. Talk about using the potty. And never discipline or get angry when she has an accident or even if it seems that she's purposely peed on the floor. I saw that both of my grandkids would stand or squat very still as if frozen when they needed to run to the bathroom. It was as if they knew they were to do something but didn't quite know how to do it. Sometimes they would quietly stay behind the sofa or chair. That was another clue. This is all brand new to them.
I've read on this site that some mothers do a "potty dance" which sounds sort of like cheerleading. We always clapped our hands and praised them for "getting the job done." High fives work too.