In this folder you must create a new folder named after your mod for the purposes of this guide I shall call it 'My Mod'. Within the 'Crusader Kings II' folder you will find the 'mod' folder, if you don't then create a new one.
Starting from your 'Documents' folder (or 'My Documents') we must navigate to 'Paradox Interactive'. By doing it this way one is forced to copy any needed files, thus avoiding messing up one's CK2 installation. To do this we will be creating a new mod directory within CK2's mod folder found in the Documents folder (AKA 'My Documents' in Windows XP).
This guide will help you, potential Crusader Kings II modder, to setup your mod so that it is possible to load it into the game from the CK2 launcher.
This shows the old method of using the 'mod' folder found in the main CK2 directory.