just make a mii and go to the plaza and choose the one you want to be the main mii!
The 3DS' 'main' mii is used on the friends list and Letterbox for example, but you can specify a different one for the streetpass games on the Mii plaza.
Mii Plaza is for Streetpass content. When you pass by another person with a 3DS, the two systems will exchange data, and their Miis will show up at the plaza. Each Mii can be used to play the Mii plaza games, 'Puzzle Swap' is the default game, though more can be purchased.
Find Mii/Streetpass Quest (depending on the region you are in) are installed onto a 3DS by default, they're part of the Mii Plaza.
It lets you make a Mii, which is a little animated character used in various other places on the 3DS, such as the Mii Plaza games, your friends list, Letter Box, etc.
StreetPass Mii Plaza happened in 2011.
For getting extra options in games (like in Augumented Reality) or for StreetPass Mii Plaza for carrying on the game(s).
3DS is better. It has Mii Plaza and Mii maker. Its in 3D. It has face raiders, will have pokedex 3d, camera setting upgraded, game memos, ect. Also, theres a 3ds game called Super Pokemon Scarmble i think its called. it will come out one day. Better get it when it comes out
StreetPass Mii Plaza was created on 2011-02-26.
The green light means you encountered someone through the streetpass and you need to visit the mii plaza to make it stop -------------------------------------------------------------------------------------------------------- Keep in mind it can also mean that there's NOT a person in the mii plaza; the 3ds simply faultily puts a green light on, sometimes. It should go away after an hour or 2?
Turn on your 3DS, select mii maker, and select create new mii and select either start from scratch or create from photo. (I personally prefer start from scratch) Then pick the gender (male or female) and you're ready to go!
go onto mii maker. then make a mii.