How to add an << Prev Next >> Navigation Button in the top or bottom of article view instead of back to TOC to view next or previous article. Where to put the code and in what .tpl file?
Assuming OJS 2.4.x, the article templates are in templates/article:
If you were to create a plugin to handle this, you could hook Templates::Article::Article::ArticleCoverImage above the article, or either Templates::Article::MoreInfo or Templates::Article::Footer::PageFooter below it.
If you were to edit the code directly, you would need to modify the desired template file and add code to the pages/article/ArticleHandler.inc.php to populate template variables with the previous and next links.