NIH has put together a web site to explain compliance and provide instructions on submission guidelines. Submission takes about 10 minutes, but there are also many journals that do the submission to PubMed automatically.
The NIH Public Access Policy ensures that the public has access to the published results of NIH funded research. It requires scientists to submit journal articles that arise from NIH funds to the digital archive PubMed Central (http://www.pubmedcentral.nih.gov/). The Policy requires that these articles be accessible to the public on PubMed Central to help advance science and improve human health.
For Submission process, policy details, and FAQ, visit: http://publicaccess.nih.gov/
