Your real name will be on your badge anyway, along with your badge name, so keep that in mind when you choose your badge name.
A lot of the people from the forums will probably put their forum names there, I probably will, it's just the default thing. Cosplayers will also use it for the name of whomever they may be cosplaying.
Please use the help forum for questions like this. It gets just as much traffic as General Discussion when new posts appear in it.
And please use the subject header to make your topic identifiable. You don't know how many "quick question"s I have to rename.