As beginner of Hacker, somethings like HACKING WIFI or HACKING BANK are prejudice about hacking.
if you want to hack somethings, you have to know their base (like Algorithm, tools, systems).
in this point of view, your question is SO WIDE to answer. if you really want to hack someones Wifi, you have to study about Wifi.
p.s. plz use Korean, It's korean forum.