Put the sd card into the wii, and start up a brawl. Press + or 'Start' depending on the controller, follow the on screen help to zoom in and out, rotate, etc. then press 'A' to take the screenshot. It will give you 2 options: save it to the wii, or save it to your sd card. Choose the latter.
Pop out the sd card, and either insert it into the sd slot of your computer, or into the digital camera. If you don't have an sd slot (I don't, I'm using a macbook) then put it into the digital camera and plug the camera into the computer.
If you're running Windows:
Wait for the dialog box to come up and select 'Show Files/Folders' or whatever it is (I forgot what it says).
If you're running Mac Os X:
Wait a bit, then look on your desktop for the external disk. Open it up.
Either way, your at the root of your sd card. Now your screenshots are stored in the following location, so go there:
You'll see some .bin files with what looks like random numbers. However, the format goes like this:
Locate the screenshot you want, or just select them all, and copy them to a folder on your hard drive.
Go to this website:
Once there select or de-select 16:9 Widescreen, depending on your options in brawl (by default it is 4:3). Click 'Choose File' navigate to your .bin screenshot, click Decrypt, and wait for it to render a .jpg. Hooray! Your Finished!