The same searching skills we use as researchers at a well-resourced institution such as UW-Madison will lead us to find and access freely available resources.
Google searches will occasionally lead to closed or fee-based resources, but are a great path to open materials too.
Communicating directly with colleagues can help you identify useful materials and, if a resource is only available in a closed or fee-based system, you can often obtain a copy by contacting the author directly.
Specialized search engines, many of which you may use to locate resources now, are more likely to be publicly available than the underlying full-text content. Once you have an author or citation in-hand, you'll be better able to locate a publicly available version.