This is just some useful information if you wanna share your friend codes with other people:

• Your friend code is the 12-digit number (0000-0000-0000) automatically assigned to you the first time you access the Nintendo Wi-Fi Connection any NWFC game. A notice will appear when you do this to show you what your code is. (Be aware that if you have other Wi-Fi compatible games and have a friend code on them, you will have different 12-digit codes for each game; they are not the same throughout!) If your game is featured on other consoles like the 360 or PS3, then you will need to share your profile names.
  
• You then exchange your codes with another person who owns the game you do and register that to your friend roster found in the Wi-Fi menu of the game. When both of you have registered each others codes, you are officially buddies and can start playing together wirelessly!

To use this forum appropriately, here is what you should do:

• Make yourself a new topic with the title: "[username] Friend Code for [game]". Then post your 12-digit number in this new topic and wait for others to reply.
  
• When you find someone to trade codes with, confirm it in either user's topic and let the game begin!
  
• It is the same principle when exchanging your profile names for the 360 and PS3, only it is not for Wii codes. You basically exchange usernames instead.

Please be aware that you do not have to share your friend codes/usernames if you do not wish to.

That is basically it, stay tuned for more details!

What about for the DS? DSes have friend codes too.

Oh, I may have forgotten that there is a DS version of Guitar Hero too. Well, yeah, what you say.

Yes they do. But it's not an online thing.