I'll explame how to use Gecko OS, with imported (for Europe: American and Japanese) games.
We'll use the NTSC/U version of Super Smash Bros. Brawl.
Go to your SD Card (mostely /media/disk, if not, go to /media and choose whatever you think your SD Card is).
Go to the "apps" folder (if you don't have one, create one).
Place the geckoos directory in there.
You'll see the Gecko OS's "boot.elf", "icon.png" and "meta.xml".
If you don't see icon.png or meta.xml (or both), the icon you can create, using GIMP (or Photoshop) at 128x48 pixels, must be .png.
For the meta.xml example code, see below this document.
Start up your Wii.
As you can see, the PAL Wii can't read a NTSC game (and vice versa).
Note: Australian games can be played on an European Wii and vice versa.
Don't worry, just go to the Homebrew Channel (if you don't have it, install the Homebrew Channel through the Twilight Hack).
Click Start.
As soon as your Wii has detected your SD Card, choose Gecko OS.
Note: Insert your SD Card before you enter the Homebrew Channel, or it will not detect.
Click the fucking Start button.
Choose Config Menu every time you use the Gecko OS.
Pick the settings.
For Japanese games, I recommened, NTSC and Japanese.
For USA games, NTSC and English.
For EU games, PAL60 and any language, exapt Japanese.
Launch the Game!
You'll see all the information.
Congrats!
You got the American Super Smash Bros. Brawl running on your European Wii!
Remember the biggest diffrents between Freeloader and Gecko OS: Datel's commercial Freeloader works for Firmware 3.2 and below, and Gecko's Open Sourse Gecko OS works with 3.2 and above! :D