1) Type into Google: "Package manager for Ruby/Nodejs/PHP/Python/etc"
2) Find a site that lists packages for that language in order of downloads per day or week.
3) Look at the top packages to see what the most popular frameworks are. Generally the top 5 - 10 packages will be all you need to develop 95% of basic projects.
4) Look into the repos for each of the top projects and look for an "examples" folder. Most top projects will have basic examples that will not only bring you up to speed on common language patterns, but also help you learn the most common and most useful methods of that framework.
5) Import any packages you need for your own project, copy a relevant example from one of the packages to start it off, and begin customizing.
Personally I learn best by example, and I find that the examples in the top frameworks and packages for any language are all I need to get up to speed in a day or two.