After downloading the mod, use a program such as 7zip or WinRAR to extract the main folder of the mod.
Drop that folder into the mods folder which is supposed to be in the game's installation folder (don't know where that is? click here)
Youll need a text editor i reccomend Notepad++ download link here: https://notepad-plus-plus.org/downloads/
but you can use whatever you like
if you want to rename the folder please do i dont mind
to edit the actual names open: difficulty.lua
and to edit the name in game and the author open: main.xml
note: open wityh the text editor