I think white noise is the specklies you get sometimes in your pics. (Like a pixel here and there end up white) maybe... I dunno.
ISO is the film speed in 35mm cameras. In digital, it's the same idea. The higher the ISO, the less light you need, but the more grainy the pic is.
SCN1 and SCN2 are probably scene 1 and 2, which would be some sort of preset settings on your camera.
Good luck! I hope you have fun with it.
Are you going to post some pics?