Many birds that have never experienced bathing will resist it, often vigorously or with fright. Others take to it almost immediately.
My routine was always to offer large, flat, shallow water dishes in the bottoms of the cages. I used both glass salad bowls and heavy duty plastic plant saucers, depending on the size of the cage.
To encourage bathers who'd never seen it before, I would float greenery (parsley, romaine) in the water to encourage investigation. Some would take to it, some would not.
Teaching them to bathe may be easier with running water in the kitchen sink, especially if you have an aeration attatchment on the faucet. The sound of rushing water, such as the faucet, or falling rain, often stimulates something within the bird's brain that is a mechanical response (rather than learned) and may help to break the Bathing Barrier.
Other people find that running the vaccuum cleaner will stimulate bathing -- this is also White Noise, the same as rushing water, which is evidentally what sparks this response.
If all else fails, I would try filling a plastic spray bottle made for misting plants and such (new clean one please) with warm water, and try spraying a gentle mist up over the top of the cage, so that if falls down and lands on the bird, rather than squirting it directly onto the bird. This often stimulates a bathing response; some of my hens would be so enthusiastic that they would be hanging upside down off the perches with wings extended to bathe every bit of their skin and would not want to stop even when they were sopping wet.
If you lower your house temperatures at night, it is better to bathe the birds in the morning, so that they are thoroughly dry before the temperatures lower.