Is there any simple way of referencing papers?
There are three simple ways to do that.
there is some extra software to do that?
Any text editor is enough to make/edit a reference database in BibTeX format (files with .bib extension) as the References,bib showed in above the limked answer.
Said that, there are several tools that in some way or another help you with this tasks. This include several LaTeX editors because the syntax highlighting or something else, bust mostly to specific tools for management of bibliographic references.
One of the best tools is effectively Zotero. Try also Mendeley, kbibtex (if you use Linux) and of course JabRef (I usually use this), but there are others as bibus, even in text mode as bibcursed (Linux).
Any place with helpful information to learn about how to reference papers?
Basic use of BibteX is explained in almost any LaTex book and Internet LaTeX tutorials. See What are good learning resources for a LaTeX beginner?
Of course, this site is also a good place to learn. Start with the most upvoted quuestion of the related tags as "bibtex". For instance, if you want to use biblatex start with
bibtex vs. biber and biblatex vs. natbib and What to do to switch to biblatex? and Guidelines for customizing biblatex styles, etc.
Any example of referencing a paper will be welcome.
Already done, but only in this site you can find hundreds (may be thousands) of additionals examples. Just search them.
.bibfile and usebiblatex+biber. An excellent tool to create such files is with the multiplatform softwareJabRef. – Bernard May 26 '17 at 00:42