Step 1Download the skin and extract the file (using either 7-Zip for Windows or The Unarchiver for Mac).
Step 2Place the "fmgraphics white" folder into your skins folder:
Windows: \Documents\Sports Interactive\Football Manager 2015\skins
Mac OS X: /Documents/Sports Interactive/Football Manager 2015/skins
Create the folder "skins" if it doesn't exist.
Step 3Start the game and go to Preferences screen and Interface tab.
You should see "FMGraphics White Skin" as option in the skin drop down of the Overview box.
Hit the Confirm button.
Please note this skin is provided as is. It has nothing to do with Sports Interactive or SEGA and won't be supported by them.