Word processing programmes usually have their own citation/reference making component, but there are other tools that can be used. Among others: Monash University Library (with a quick guide and interactive online tutorials), BibMe, Citefast. There are two major programmes used for handling citations: Zotero and Mendeley.

Zotero 

Zotero is a complex referencing programme. To get acquainted with it the following sites may be useful: https://www.youtube.com/results?search_query=zotero+tutorial
This is probably the best one to start with: https://www.youtube.com/watch?v=mP5AzJHXfIA
And this one explains how to insert it into Word docs: https://www.youtube.com/watch?v=imSxa5MbXrc

The Faculty of Pedagogy and Psychology (PPK) offers training for ELTE students and employees: https://konyvtar.ppk.elte.hu/content/felhasznalokepzes.t.30556

Mendeley

Mendeley is similar to Zotero, and several tutorials are available for it online.

The commonly used word processor 'Word' also has a referencing tool under the "References" tab, and tutorials on how to use it can be found online.