1. You need WinRAR
2. This is a PC tutorial
3.Lets go

Get the mod you want to install and open it make sure it opens in WinRAR
Now click on windows and type in were it says Search programs and files %appdata%
Then click .minecraft
Then click Bin
Then Right click Minecraft and open with WinRAR
Now you should have Minecraft and your mod open with WinRAR
Drag and drop everything from your mod except the ... file at the top into the Minecraft WinRAR
Now in the minecraft WinRAR Delete META.INF
You can now open minecraft and enjoy your mod!

:)