This file includes two zipped savegames from Need for Speed: Most Wanted. One has all missions completed in career mode and the second is saved at the last mission.
Open the zip file that you want to use and extract the files to your Need for Speed: Most Wanted save folder. The default is C:\Documents and Settings\USERNAME\My Documents\NFS Most Wanted.
When you start the game, select the profile "zero" and then choose Resume Career Mode.