nginx can be installed differently, depending on the operating system.
For Linux, nginx packages from nginx.org can be used.
On FreeBSD, nginx can be installed either from the packages or through the ports system. The ports system provides greater flexibility, allowing selection among a wide range of options. The port will compile nginx with the specified options and install it.
If some special functionality is required, not available with packages and ports, nginx can also be compiled from source files. While more flexible, this approach may be complex for a beginner. For more information, see Building nginx from Sources.