I have the zip file from the site but im confused what i should do next.
If you want to install a mod, you put the zip in the mods folder. You will however need to have forge installed first. I recommend using the installer to do so. The mods folder will appear on the start of your minecraft AppData/ApplicationSupport folder.
Note that sometimes zip files have to be extracted, because they contain another zip in them. If you want your mod to be installed correctly, the mod data has to be on the start. There are cases in which a zip contains a readme text, and a folder with the mod data. You will want to archive the contents of that folder and put that in your mods instead.