Potty training help

I need help with potty training my 21 month old. She sits on her potty chair every time before a bath and has since she was 12 months old. But she’s only actually used it once and that was months ago, so that was just luck lol.

How do I start trying to really teach her? How often do I take her to the potty and when do I take her? And how long should I have her sit on there at a time?

I have her sit on her potty and read her books. Any other sort of tips? She isn’t really talking yet so I’m sure that makes things harder