New to Java

Hello,

I need to create a java file that reads input which would be the message to encode, it then writes it to an output file which would be the message encoded, and it asks for the offset. I am hopelessly lost on how I am to go about doing this, I've asked a couple people on how to do this, but I just don't understand how, I've used google, but nothing is really similar to what I am supposed to do, so if I can get any help whatsoever, it would be greatly appreciated, and I'm only doing this as a last resort.

Thanks,

Brett