You can install Webmin by either downloading and installing the RPM directly or you can add Webmin to your repo list then use DNF to install Webmin; I prefer the latter method.
First, make sure your Fedora installation has the prerequisite dependencies installed. These dependencies are usually resolved and installed by DNF but I like to install them beforehand just to be safe. I also install vim and wget at the same time for convenience.
dnf -y install vim wget perl perl-Net-SSLeay openssl perl-IO-Tty
Second, create a repo file for Webmin:
Press the “I” key then copy and paste the following in your Webmin.repo file:
name=Webmin Distribution Neutral
Save this file by pressing “Esc”, then “:”, then “x” (this will save your changes and exit VIM), then press “Enter”.
Third, install the Webmin GPG key:
rpm --import http://www.webmin.com/jcameron-key.asc
Fourth and finally, install Webmin:
dnf -y install webmin
You should now be able to open your favorite browser and browse to https://servername:10000/