1. Download CM08 through
this thread
2. After Downloading CM08, open CM08. Then go to File ---> Open - Fifa 08
Wait until that opens and you can see the graphic menu options (this may take a minute or two).
3. From the menu click on Patch ---> Load
***Note: By this point you should already have a stadium to import. If you don't, you can find many from '07 to import
here.***
4. The CM08 Patch Loader screen should open. Click on the load button and navigate to wherever you placed your stadium to import (it should be a .cmp file). You may need to wait a minute for this to load.
5. Once this is done, go to the right side of the window and there should be both a create and a replace radial button to check. Check the create option if you are adding a stadium to the game.
6. Click on Import button and wait for the completion. The CM08 Patch Loader screen should disappear when it's finished.
***Now you still have to make sure that the stadium is being used by the team that you want.***
7. With CM08 still open, click on the Team icon (looks like the Arsenal logo). Just under the graphic menu options to the far left is a drop-down box to select which team you want. Select the team you want. And then further down is a stadium section. Use the drop-down box there to find the stadium that you just imported. Not sure if it's necessary, but i always click on File ---> Save after i'm done adding all my stadiums before i close CM08.
Hopefully this helps. =)