Step 1: Get the RPM, run this command
    wget http://prdownloads.sourceforge.net/webadmin/webmin-1.520-1.noarch.rpm

Step 2: Install the RPM, run this command
    rpm -U webmin-1.520-1.noarch.rpm

Step 3: Open the firewall on port 10000. Run this command
    iptables -I INPUT -p tcp --dport 10000 -j ACCEPT

now you can access webmin via http://server:10000 using your shell credentials.

Enjoy!