Due to the centralized hosting of files and data retention, Leeching is encouraged
The net result of these things is that you can download files extremely quickly, securely, anonymously, and without reciprocation. The downside is that you generally need to pay for a subscription to gain access to binary files hosted by super fast servers with long data retention.
You need a few things to get up and running:
A subscription to a Usenet Server
A news reader application
An NZB indexing site
Once you have those two things, you'll need to configure your news reader software to access the Usenet server you’ve subscribed to. It's a fairly straightforward process involving adding a new server to your news reader, the details of which are provided by your choice of Usenet server. For example, the setup instructions to configure NewsLeecher with NewsHosting can be found over at newsgroupreviews.com.
3) Now that you're set up to retrieve files from a Usenet server you just need to find them. That's where the NZB index sites come in. These sites provide searchable lists of available binaries and links to the NZB information files that allow you to download them. You may need to shell out again for access to a few of these but the cost is usually very low, for instance NZBMatrix is about $1/year. Another popular option is the creator of the NZB file format itself, NewzBin.