First go to http://www.7-zip.org/
Download 7zip, its safe dont worry. Now right click on the .rar folder and you should see a "7-zip" or something like it. Choose the option with extract in it, and do it to where ever. Now open up the extracted battlefront extreme folder and it should have a readme which will explain how to install the mod, if not post again and Ill dig that up for you.