How to open a confirmation window after submit?

Question

fancyBox

There is a fancybox modal window opened by the inline method
. It contains an order form.
after submitting the form, it closes. and I need it to either show the inscription Thank you, your order is accepted, or open a new window with the following text,
how can I do this?
When you open the iframe method, everything is clear and simple - but here I just can’t understand