WHAT IS USENET?
WHY NOT BITTORRENT?
WHAT'S THE CATCH?
Step 1: Choose a provider.
Most will do you just fine. You'll want to judge your needs based on how much you think you will download in a month. You can also opt for an unlimited plan if the host provides it. Some standard features you'll want to find are hosts that provide encryption, and are fast enough to match your internet speed, or a plan with no speed restrictions. You'll also want to check out their "retention" rates. Retention specifies how many days worth of content the service archives. So, if the retention is 60 days, that means you can't download files or read messages that are more than 60 days old.
I use Supernews. I also have high praise for Giganews, but it tends to be the most expensive of the bunch.
Step 2: Get the software.
Once you sign up for your service, you'll need software to decode the messages and download the files. I recommend Alt.Binz. Install the application, and open it up.
Click "Servers" on the left. Your newsgroup provider will have e-mailed or otherwise provided you with the information to fill in. When you're done, click "Apply" and then "Add as primary." Press "OK." At the top of the screen, press the "Connect" button. You should see "Connected and authenticated" at the bottom. If not, check your server settings and try again. You may also need to wait a period of time before your account is active and ready to use.
Step 3: Find what you're looking for.
When the NZB has finished downloading, go back to Alt.Binz. Press the "Connect" button if you're not already connected, and then press "NZB".
Find the NZB file you downloaded, and open it. Your file will begin to download! You'll need WinRAR, or 7-Zip to extract the files you downloaded if they are contained in an archive. Just download the software from here and install it. You'll be able to just right-click on your downloaded files and press Extract.
That should be all. Any questions, feel free to holler!