The goal of fpm is to make it easy and quick to build packages such as rpms, debs, OSX packages, etc.

fpm, as a project, exists to help you build packages, therefore:

If fpm is not helping you make packages easily, then there is a bug in fpm.
If you are having a bad time with fpm, then there is a bug in fpm.
If the documentation is confusing, then this is a bug in fpm.
If there is a bug in fpm, then we can work together to fix it. If you wish to report a bug/problem/whatever, I welcome you to do on the project issue tracker.

You can find out how to use fpm in the documentation.

You can learn how to install fpm on your platform in the installation guide.