The sections are described in the Submission Guidelines, which you should review before submitting an article. If you are not sure for which section your article would be most appropriate we will be glad to suggest an appropriate section after we have reviewed the article.
Perhaps the major issue on which the "Publication Manual of the American Psychological Association" (APA Style Guide) guide should be consulted is to how source materials should be cited. This publication and simplified APA style guides can be found in libraries.