#12 Error: Cannot create %sourcedir /usr/src

[Anonymous]

I typed (in the /tmp/ directory, where I downloaded the
rpm file):

rpm -U webmin-1.000-1.noarch.rpm

Almost right away, I got this error msg:

Error: Cannot create %
sourcedir /usr/src/redhat/SOURCES

I checked and there exists /usr/src/ but no /redhat/
directory.

How do I install webmin?