How to use folders for tags

I'm very new to this software. I tried looking online, but I couldn't figure out how to do what I wanted to do.

My music is sorted like this, where each (Word) is a folder and each [Song] is an mp3 file:
(Genre) - (Artist) - (Album) - [Song]. (To clarify, there are folders representing Genres, then folders representing Artists, then folders representing Albums.)

What tool or action should I use so I can correctly tag each mp3 with the correct Genre, Artist, and Album from these folders automatically? A specific answer if possible would be greatly appreciated.

See the FAQs and HowTos on data import from folders.
Also, the help would have dealt with this topic.

..or, if you don't want to read any f....antastic manual, just mark your files, select

Convert -> Filename - Tag Alt + F2

and enter the following string

%genre%\%artist%\%album%\%track% - %title%

Omit %track% - part, if you don't have the tracknumers stored in the filename.