A problem I'm having with Mugen

[tokusatsufan]

I didn't know where else to put this. I don't know if this kind of thing is allowed. If not then at least tell me how to do this please. I downloaded Mugen,I'd been meaning to for ages,I downloaded characters and I read about changing the text in that .def file,so I did that but they still aren't in it when I open it up. Can anyone tell me what to do because I'm really new to this? Did I edit it wrong?!

Thank you.