basically once you've made changes it will ask you to name it and then you save.
the database folder is saved in:
My Documents\Sports Interactive\Football Manager 2007
you have to now move this folder to:
C

Program Files\Sports Interactive\Football Manager 2007\data
Start the game like normal and at the Main Menu Screen click on the Preferences button.
In the bottom half you see "User Data Folder" now change that path to the folder you just moved.
e.g C

Program Files\Sports Interactive\Football Manager 2007\data\nameyouchose
Confirm it and go to start new game and it should give you the choice of which database to use.
hope this helps.