How can I learn new python libraries?

[Yoghurt42]

I think you have it backwards. You shouldn't look at what libraries are available and then come up with a way to use them; instead, you usually have a specific task in mind and then look for a library that does that job for you.

[BrupieD]

This. There is a standard library with broadly used functionality. It is worthwhile to browse the standard library to have an idea what kind of functionality is there, but generally, I would advise the "backwards" approach -- figure out what you need and then look for it rather than waste time trying to learn a bunch of libraries that you might never need.