I am assuming that you used winrar to extract the files to the desktop. If not then use
http://www.rarlab.com/rar/wrar351.exe to extract the files to the desktop.
"To install, Put the Foc additions folder in the Mods folder in star wars empire at war forces of corruption directory in lucasarts
included is a .ink program, extract this to your desktop and use to start foc additions
click on this to start the mod"
What this means is open My Computer, click on the Local Disk, click on Program Files, then LucasArts, Then the FOC folder, then right click and choose new folder and name it Mods. Then copy the FOC addon folder to the new mods folder in the program files and copy the .ink file to the desktop. Put in the FOC disk and click on the icon on the desktop to start.
Hope this helps.