To use newsgroups to.... backup your files... you need to be subscribed to a news server. Some ISP will provide a free account, but the retention time, speed, and parity simply ****. The big one is Giganews, but there are tens of good companies. It costs about 10$ per month for unlimited access. It is NOT a p2p protocol, it is a client-server protocol. Anyways, you need to browse or get a .nzb index file to download your files, along with a software. I would recommand "Grabit" because it is free, but there are tons of other softwares, like with torrent clients.
Note that you will always get full speed on those servers, and you will find a lot of material. Very nice way of getting your.... things...