When your paper has been accepted for publication, you need to do two things:
1. deposit the paper in ORA (via Symplectic) -- click here after reading these notes on configuring Symplectic and some current Symplectic bugs.
a) I have Acted on Acceptance but recent articles are not appearing at the top of my list -- why?
b) How do I add a Date of Acceptance (DOA) to an already 'claimed' publication record?
c) How do I enable someone else to be a 'delegate' to deposit papers for me?
There is also a university webpage with FAQs on Open Access and the next REF, including the definition of the Date of Acceptance.
2. deposit the underlying data in ORA-data -- further information is available here.