The NIHMS has a new look as of December 12, 2014.
There are four methods of submitting the applicable paper to PMC. Authors may use whichever method is most appropriate for them and consistent with their publishing agreement.
Method C: Author deposits final peer-reviewed manuscript in PMC via the NIH Manuscript Submission System (NIHMS). Three-step process, video demonstration: Submitting an Article to PubMed Central (wmv 12:01)
Method D: Author completes submission of the final peer-reviewed manuscript deposited by publisher in the NIHMS.
Include the PubMed Central reference number (PMCID) at the end of citations
For papers in press, or published within 3 months of when an application, proposal or report is submitted:
PMID: PMCID Converter. Given a set of PubMed IDs (PMIDs) you can use this converter to obtain the corresponding PMCIDs and/or NIHMS IDs if they exist...