I would check first to see if she has an infection (UTI, bladder) that's causing pain. The doctor can test her easily for that. Once you have ruled that out, I would go easy with her if you aren't sure she's ready. Some kids would be old enough at this age & others not so much. It really goes by individual maturity levels & temperament.
We didn't even bother starting with our son until he was nearly three. We started by giving him his new, unused potty to tote around the house. We said nothing about poo or pee at first. He sat in it while he watched tv or listened to a book. It became 'his' and so he didn't find it scary or threatening. He was actually kind of posessive about it.
After about a week, we explained that the potty would stay in the bathroom & if he wanted to sit on it while Mommy read a book to him, he would need to pull down his pants & sit on it in the bathroom. I sat on the floor next to him everyday after meals about the time he normally dirtied his diaper and first read a book by Dr. Sears for kids about learning to use the potty. It was extremely simple with pictures of another little boy going through the motions. Then we would usually look at a book like Richard Scarry's Cars & Trucks & Things that Go. Something that had a lot of detail & interest for him & kept him happily seated on the potty for a good 20 minutes.
Most of the time we'd be reading and he would be completely distracted and all of a sudden he'd go potty. He'd look at me like, "What was that?" I'd smile & clap & say, "You went potty in your big boy potty just like Johnny in the book!" We'd make a big deal about his 'success'. Then I'd let him 'do the honors' of dumping the contents into the toilet and flushing. He loved it. We'd clean him up and go to the kitchen for an M&M reward. He got one M&M for pee & two for poopie.
My husband was just as involved when he was home, so Jack saw the whole thing as fun & a great way to get lots of positive attention from Mom & Dad both. We'd ask him from time to time if he needed to go, but we didn't fuss when he had accidents. We just acted like they were not very interesting as we cleaned him up. The M&M's, story time & positive reinforcement were enough to keep him coming back on his own after a week or so.
I laugh at this memory, because the only times he'd really get upset were when he'd try to go & couldn't. He wanted an M&M & the thrill of success more than anything! Of course we always praised him for trying, but no M&M's. He had the hang of things within two weeks & we were completly beyond all daytime accidents in just a few months. :)