How to create an rpm from installed files?

i would like to package up an rpm from pre-installed files, say i have a program called "widget" installed under "/opt/widget"

/opt/widget/bin/*
/opt/widget/lib/*
/opt/widget/etc/*
/opt/widget/log/*

and i want to create an rpm from those already installed files, what would the spec file look like? just to be clear, there's no need to build/compile/configure anything, just to bundle the already installed files into an rpm

If there's no need to configure anything then just copy the files over to the new location.

You need a Tarball and a Spec-File to do a rpmbuild-command. That should build you a rpm-package.

Greets