Where do I upload files?

Hello guys.

Maybe I'm doing something wrong, but I'd really appreciate if someone could
tell me where do I upload the ISO files for DVDs and smaller ones for other
purposes.

I'm trying to upload some files to (small ones) to
brasil.libreofficebox.orgbut, no matter what I try, I always receive
an error message saying there's
an I/O problem. I have no idea of what's going on.

Someone, please help.

Thanks and Rgds