Anton's link is useful. To upload for public view will depend on the journal's copyright policy - and how old the article is. For individual 'private' requests - you are free to do that with any article.
In most cases, publishers do allow you to share privately with colleagues – albeit it is typically via a link, rather than a downloaded PDF copy. All the major publishers have a policy on restrictions for sharing; the policy can normally be found on their website.
Distribution of your findings after publishing your manuscript is one of the goals of the research. Social media and ResearchGate are used in this purpose. It may also allow you to receive feedback and comments on your work.